Generate HTML documentation using MkDocs (WIP)

MkDocs is a static site generator geared towards building project documentation.
Documentation source files are written in Markdown, and configured with a single YAML file.

 * http://www.mkdocs.org/
 * http://www.mkdocs.org/user-guide/configuration/

Ref. #312

* remove pandoc-generated HTML documentation
* move markdown doc to doc/md/,
* mkdocs.yml:
  * generate HTML doc in doc/html
  * add pages TOC/ordering
  * use index.md as index page
* Makefile: remove execute permissions from generated files
* Makefile: rewrite htmlpages GFM to markdown conversion using sed:
   awk expression aslo matched '][' which causes invalid output on complex links with images or code blocks
* Add mkdocs.yml to .gitattributes, exclude this file from release archives
* Makefile: rename: htmldoc -> doc_html target
* run make doc: pull latest markdown documentation from wiki
* run make htmlpages: update html documentation

1 files changed, 75 insertions, 0 deletions

diff --git a/doc/md/Plugins.md b/doc/md/Plugins.md
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+## Plugin installation
+
+There is a bunch of plugins shipped with Shaarli, where there is nothing to do to install them.
+
+If you want to install a third party plugin:
+
+  * Download it.
+  * Put it in the `plugins` directory in Shaarli's installation folder.
+  * Make sure you put it correctly:
+
+```
+| index.php
+| plugins/
+|---| custom_plugin/
+|   |---| custom_plugin.php
+|   |---| ...
+
+```
+
+  * Make sure your webserver can read and write the files in your plugin folder.
+
+## Plugin configuration
+
+In Shaarli's administration page (`Tools` link), go to `Plugin administration`.
+
+Here you can enable and disable all plugins available, and configure them.
+
+![administration screenshot](https://camo.githubusercontent.com/5da68e191969007492ca0fbeb25f3b2357b748cc/687474703a2f2f692e696d6775722e636f6d2f766837544643712e706e67)
+
+## Plugin order
+
+In the plugin administration page, you can move enabled plugins to the top or bottom of the list. The first plugins in the list will be processed first.
+
+This is important in case plugins are depending on each other. Read plugins README details for more information.
+
+**Use case**: The (non existent) plugin `shaares_footer` adds a footer to every shaare in Markdown syntax. It needs to be processed *before* (higher in the list) the Markdown plugin. Otherwise its syntax won't be translated in HTML.
+
+## File mode
+
+Enabled plugin are stored in your `config.php` parameters file, under the `array`:
+
+```php
+$GLOBALS['config']['ENABLED_PLUGINS']
+```
+
+You can edit them manually here.
+Example:
+
+```php
+$GLOBALS['config']['ENABLED_PLUGINS'] = array(
+    'qrcode', 
+    'archiveorg',
+    'wallabag',
+    'markdown',
+);
+```
+
+### Plugin usage
+
+#### Official plugins
+
+Usage of each plugin is documented in it's README file:
+
+ * `addlink-toolbar`: Adds the addlink input on the linklist page
+ * `archiveorg`: For each link, add an Archive.org icon
+ * [`markdown`](https://github.com/shaarli/Shaarli/blob/master/plugins/markdown/README.md): Render shaare description with Markdown syntax.
+ * [`playvideos`](https://github.com/shaarli/Shaarli/blob/master/plugins/playvideos/README.md): Add a button in the toolbar allowing to watch all videos.
+ * `qrcode`: For each link, add a QRCode icon.
+ * [`wallabag`](https://github.com/shaarli/Shaarli/blob/master/plugins/wallabag/README.md):  For each link, add a Wallabag icon to save it in your instance.
+
+
+
+#### Third party plugins
+
+See [Community & related software](https://github.com/shaarli/Shaarli/wiki/Community-%26-Related-software#third-party-plugins)