Tags in com_content - Distinction between article and category tags

Bugfix of the described problem here: http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=33602&start=0

Most important thing is the introduction of the new attribute "show_cat_tags" to distinct between the tags for articles and categories. The output and control of the tags for the different layouts (featured, blog, article) was also improved.

How to test?

Create some articles and categories with tags. Also create menu entries for the described layout views. Now play around with the different setting possibilities -> Enable and disable the option "Show Tags" for articles and categories in

- menu entries
- global settings
- article

Plus in the pull request: many code styling improvements