youtube/vimeo/video tag improvements

- Allow more flexible video identifiers, current one "\w" blocks e.g.
youtube identifier "ul-FqOfX-t8". New one allows also attaching
positional arguments to video, e.g. "ul-FqOfX-t8#t=123"
- Surrounded each video element with a div having "videobox"-class for
styling purposes (e.g. center alignment)
- improved code formatting
Fixes #193 Adding TEMPLATE_PAGES to tipue_search plugin
Fix outdated link to Pelican docs
Merge pull request #194 from Futurile/template-pages-search

Add TEMPLATE_PAGES to tipue_search plugin. Fixes #193
[tipue_search] Restore support for Python 3
Merge pull request #230 from Schnouki/patch-1

[tipue_search] Restore support for Python 3
Merge pull request #207 from jojanaho/master

Liquid tags: youtube / vimeo / video improvements
PLUGIN_PATH setting has been replaced by PLUGIN_PATHS and it should be a list
Merge pull request #233 from 2xyo/master

Migrate Readme.rst documentation to PLUGIN_PATHS
[post_stats] Python 3 compatibility

In Python 3, `filter()` returns an iterator instead of a list, which causes an error on line 42: "object of type 'filter' has no len()". Using a list comprehension fixes this, and is probably a little more readable.
Merge pull request #234 from Schnouki/patch-2

[post_stats] Python 3 compatibility
Properly encode author in comments
Merge pull request #235 from jml/master

Properly encode author in comments
Allow restructuredtext comments.
Take into account some review comments.

- Automatically exclude comments path from pages and articles processing.
- Add the file extension back onto the ID.
- Update the documentation.
Update docs about the comment system dir.