Rework of the gang, and gang areas logic, and dialog, and bug fixes

- Deleted files (functionality moved around, or reworked)
* gangfunctions.sqf, gangflags.sqf, gangs.sqf, gangsserverloop.sqf,
itemprocess.sqf

- Changed the way licenses are stored and modidifed and checked (New
API)
* [_player, _license] call player_has_license
* [_player, _licenses] call player_add_licenses
* [_player, _licenses] call player_remove_licenses

- Remove global variables associated with gangs, and gang activity
* gangleader, gangmember, gang_array_name, gang_array_members,
gangsarray

- Removed the server loop that takes care of deleting empty gangs
- Empty gangs are now deleted event-driven (when last player of the gang
leaves the gang or disconnects)
- Added API for gang, and gang area related actions, in
Awesome/Functions/gang_functions.sqf
* gangs_get_list, gangs_update_list, gang_remove_member,
gang_add_member, gangs_lookup_player_uid, etc

- UIDs when used in the context of gangs is not the same as player UID
- The UIDs in the gang members list is calculated with function:
[_player] call gang_player_uid
- Added method for checking if player is in a gang: [_player] call
player_gang_member
- Fixed actions for gang shops 2, and 3 so that they show the actual
gang shop items (weapons, etc), not jus drugs
- Improved the loading screen messages to show the progress while stats
are being compiled