Switch docs to MKDocs (#602)

Fixes #601. Merged in 6f87b32 from the md3 branch and did a lot of cleanup.

Changes include:

* Removed old docs build tool, templates, etc.

* Added MkDocs config file, etc.

* filename.txt => filename.md

* pythonhost.org/Markdown => Python-Markdown.github.io

* Markdown lint and other cleanup.

* Automate pages deployment in makefile with `mkdocs gh-deploy`

    Assumes a git remote is set up named "pages". Do

        git remote add pages https://github.com/Python-Markdown/Python-Markdown.github.io.git

    ... before running `make deploy` the first time.

1 files changed, 171 insertions, 0 deletions

diff --git a/docs/cli.md b/docs/cli.md
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+title: Command Line
+
+Using Python-Markdown on the Command Line
+=========================================
+
+While Python-Markdown is primarily a python library, a command line script is
+included as well. While there are many other command line implementations
+of Markdown, you may not have them installed, or you may prefer to use
+Python-Markdown's various extensions.
+
+Generally, you will want to have the Markdown library fully installed on your
+system to run the command line script. See the
+[Installation instructions](install.md) for details.
+
+Python-Markdown's command line script takes advantage of Python's `-m` flag.
+Therefore, assuming the python executable is on your system path, use the
+following format:
+
+```bash
+python -m markdown [options] [args]
+```
+
+That will run the module as a script with the options and arguments provided.
+
+At its most basic usage, one would simply pass in a file name as the only argument:
+
+```bash
+python -m markdown input_file.txt
+```
+
+Piping input and output (on `STDIN` and `STDOUT`) is fully supported as well.
+For example:
+
+```bash
+echo "Some **Markdown** text." | python -m markdown > output.html
+```
+
+Use the `--help` option for a list all available options and arguments:
+
+```bash
+python -m markdown --help
+```
+
+If you don't want to call the python executable directly (using the `-m` flag),
+follow the instructions below to use a wrapper script:
+
+Setup
+-----
+
+Upon installation, the `markdown_py` script will have been copied to
+your Python "Scripts" directory. Different systems require different methods to
+ensure that any files in the Python "Scripts" directory are on your system
+path.
+
+* **Windows**:
+
+    Assuming a default install of Python on Windows, your "Scripts" directory
+    is most likely something like `C:\\Python26\Scripts`. Verify the location
+    of your "Scripts" directory and add it to you system path.
+
+    Calling `markdown_py` from the command line will call the wrapper batch
+    file `markdown_py.bat` in the `"Scripts"` directory created during install.
+
+* __*nix__ (Linux, OSX, BSD, Unix, etc.):
+
+    As each \*nix distribution is different and we can't possibly document all
+    of them here, we'll provide a few helpful pointers:
+
+    * Some systems will automatically install the script on your path. Try it
+      and see if it works. Just run `markdown_py` from the command line.
+
+    * Other systems may maintain a separate "Scripts" ("bin") directory which
+      you need to add to your path. Find it (check with your distribution) and
+      either add it to your path or make a symbolic link to it from your path.
+
+    * If you are sure `markdown_py` is on your path, but it still is not being
+      found, check the permissions of the file and make sure it is executable.
+
+    As an alternative, you could just `cd` into the directory which contains
+    the source distribution, and run it from there. However, remember that your
+    markdown text files will not likely be in that directory, so it is much
+    more convenient to have `markdown_py` on your path.
+
+!!!Note
+    Python-Markdown uses `"markdown_py"` as a script name because the Perl
+    implementation has already taken the more obvious name "markdown".
+    Additionally, the default Python configuration on some systems would cause a
+    script named `"markdown.py"` to fail by importing itself rather than the
+    markdown library. Therefore, the script has been named `"markdown_py"` as a
+    compromise. If you prefer a different name for the script on your system, it
+    is suggested that you create a symbolic link to `markdown_py` with your
+    preferred name.
+
+Usage
+-----
+
+To use `markdown_py` from the command line, run it as
+
+```bash
+markdown_py input_file.txt
+```
+
+or
+
+```bash
+markdown_py input_file.txt > output_file.html
+```
+
+For a complete list of options, run
+
+```bash
+markdown_py --help
+```
+
+Using Extensions
+----------------
+
+To load a Python-Markdown extension from the command line use the `-x`
+(or `--extension`) option. The extension module must be on your `PYTHONPATH`
+(see the [Extension API](extensions/api.md) for details). The extension can
+then be invoked by the name of that module using Python's dot syntax:
+
+```bash
+python -m markdown -x path.to.module input.txt
+```
+
+To load multiple extensions, specify an `-x` option for each extension:
+
+```bash
+python -m markdown -x markdown.extensions.footnotes -x markdown.extensions.codehilite input.txt
+```
+
+If the extension supports configuration options (see the documentation for the
+extension you are using to determine what settings it supports, if any), you
+can pass them in as well:
+
+```bash
+python -m markdown -x markdown.extensions.footnotes -c config.yml input.txt
+```
+
+The `-c` (or `--extension_configs`) option accepts a file name. The file must be
+in either the [YAML] or [JSON] format and contain YAML or JSON data that would
+map to a Python Dictionary in the format required by the
+[`extension_configs`][ec] keyword of the `markdown.Markdown` class. Therefore,
+the file `config.yaml` referenced in the above example might look like this:
+
+```yaml
+markdown.extensions.footnotes:
+    PLACE_MARKER: ~~~~~~~~
+    UNIQUE_IDS: True
+```
+
+Note that while the `--extension_configs` option does specify the
+"markdown.extensions.footnotes" extension, you still need to load the extension
+with the `-x` option, or the configuration for that extension will be ignored.
+
+The `--extension_configs` option will only support YAML configuration files if
+[PyYAML] is installed on your system. JSON should work with no additional
+dependencies. The format of your configuration file is automatically detected.
+
+!!!warning
+    The previously documented method of appending the extension configuration
+    options as a string to the extension name will be deprecated in
+    Python-Markdown version 2.6. The `--extension_configs` option should be used
+    instead. See the [2.5 release notes] for more information.
+
+[ec]: reference.html#extension_configs
+[YAML]: http://yaml.org/
+[JSON]: http://json.org/
+[PyYAML]: http://pyyaml.org/
+[2.5 release notes]: change_log/release-2.5.md