added defined JEXEC to recurr class
calendar: added check for venue

if there is no venue then the venue part wo't be displayed. at the
moment it displays's a " - " and it's to display nothing.
a bit of cleanup

removed/changed some language strings, etc..
eventslist-model: added definition of access_level + field c.path to query.

the path info is required to show the categories when using function
"getCategoryList" and the access-level is there to show the group in
case of using the editor-xtd plugin