[#33815] Fix for com_tags - show tags title properly - option "show tag name" + p...

...age title

(plus some code optimizations - removed unneeded references and deprecated function call getCfg)

JoomlaCode Tracker: http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=33815&start=0

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This fix adds the tags title to the page title (if no menu entry set) and the option "Show tag name" shows the correct name of the tags, not site title which is set in the global configuration.

If a menu entry is set, then the information from this entry is used. The tags component should now behave like the content component.
Can you do this function so it returns the `tags_title` instead of setting it directly as a view property and returning null?
Imho code is easier to understand then if the call looks like `$this->tags_title = $this->getTagsTitle();`