backend: fixes limitbox for joomla 2.5
Added filter, search and sort option for events to back end. Needed to rename the tags column to foldertags because of conflicts with the new Joomla 3.1 Tags feature.

fixex #9
added default event layout configuration to the components global options
fixed bad behavior if you directly link a event in the menu. The layout was pulled by the global configuration instead of from the menu.
doc update
doku update.
fixed wrong placeholder text for events search in backend