[db] Remove conroller id from permission primay key.
[php] Initial group manager implementation (not yet functional).
[php] Make DB usage consistent.
[php] Add group manager functionality (permission management missing).
[db] Add permission categories and descriptions.

DB model version raised to 2.5.
Initial MVC for Calendar
Calendar MVC

CalendarPageController renamed to CalendarController, same for the
CalendarModel, event registration form, sucess and failure added
Calendar and Event objects created (not ready)
Documentation, event registration views
Calendar Controller and Model + update of table Event
[php] Add group manager permission management functionality.
[php] Fix short opening tags and add timezone configuration.
Calendar fix
Calendar controller - different view, time selection form
Calendar-Event system (not stable)
Merge branch 'sergei_groupmanager'

Conflicts:
	backend/core/adapters/MySQL_Adapter.php
	db/create.sql
	db/src/DB_model_2.mwb
	db/test_data/10_controller.sql
[php] Cleanup DB adapter and add calendar link to main page.
[php] Fix registration (used legacy insert adapter method).
Updates for calendar and event tables, saving events, event reg.form fix
[php] Implement group manager group creation functionality.