Changed constraint relation from CASCADE to RESTRICT
Added Denkmal_Paging_Message_Venue
Extended venue model:
- with getEventList(), getAliasList(), getMessageList()
- added onDelete()
Added Denkmal_Paging_Event_Song
Remove song from events on song delete
Removed caching for paging (messages for venue)
Merge pull request #26 from kris-lab/issue-26

Introduce onDelete for models