[FIX] calendar: allow to sort in tree view the starting date (start, start_date, start_datetime) (hack for V8)
[FIX] web_calendar: improve the commit 787147d. This commit was fixing bug in other module that calendar which was open an event in popup view. Because browse/read by default was unable to read string id. The fix was too restrictif, because calendar need to read/browse string; we cannot cast this id in Int else we loose the virtual part. parseInt('12-20140512') -> 12.