LL-228
* provided calls flagsUserSet, flagsUserGet allowing to set "deadline" and "importance" flags currently
* extended SSFlag data type with user, entity, type, creationTime, endTime and value properties
* added flag and flags table for storing flags and flag assignments
* fixed getActivities in SSActivitySQLFct: wrong users and entities got added to activities form db
* fixed storing activities for discEntryAdd