Fix wrong results returned by isEnabled

When language filter plugin is disabled and language filter is enabled in code using JFactory::getApplication()->setLanguageFilter(true) calling JLanguageAssociations->isEnabled causes notices and fatal errors and returns wrong result if item associations are in fact disabled.

What happens is that JPluginHelper::getPlugin returns empty array when certain plugin is disabled and since there is no params to be passed to JRegistry and $enabled gets default value.
Missing object property "language".
Using "joomla.content.icons" JLayout for article and feature view
Several CSS fixes
[bug] [33653] Array to string conversion notice in mod_articles_category with PHP 5.4+ Strict
Close #3595
Merge pull request #3594 from roland-d/cssfixes

[#33721] Several CSS fixes
[Fix][#33037] Email Cloaking causes slower page loading in Firefox (Fix
# 2716)
Merge pull request #3177 from klas/patch-5

Fix wrong results returned by isEnabled
Merge pull request #3136 from Bakual/AddIconsLayout

Using the "joomla.content.icons" JLayout for article and feature view
[Fix][#32894] Nesting issue: beez3/catergory/blog.php [Fix #1952] Thanks
isamrx
[#33150] Use data-direction attribute to update direction (Fix #2797)
Codestyle, closes #3600
Update 3.2 --> 3.3
Close #3601
Protostar template does not highlight com_search results
Codestyle
[bug] [33732] Removed unnecessary 'if' ternary
Close #3596
Administrator lang strings overrides can't be deleted
Merge pull request #3605 from roland-d/31127

[#31127] Protostar template does not highlight com_search results
Fixed  joomla.edit.details layout saves empty language

http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=32783&start=100
Getting rid of strtoupper