retrieve of versionnr, renaming of name comp/cal, fix for #261, and more

Added retrieval of versionnumber in the updatecheckermodel. Renamed the
name of the component + calendar module to get it more inline with
joomla. Attendee-view: the columns name/emailadress/uid have been
removed from the front.  added highlighter for now. fixed ical-link.
removed versionnumber of the help-section.