[mr3148] Fix chase moving for creatures with UNIT_FLAG_DISABLE_MOVE flag

* Now DB creature_template.unit_flags && 4 (DISABLE_MOVE) will work.
[mr3149] Implement handling for base Parachute visual spell

* Now all parachutes have canopy, f.ex. Dalaran, vehicle and etc.
[mr3150] Group: fix rare crash on disbanding; some codestyle.
[mr3151] Forgotten line in mr3148, disable moving also for MoveFleeing.
[mr3152] Improve Preserved Holly item (21213) working - remove all cheat usage (mount/speed stacking)
[mr3153] Rework Festive Holiday Mount (mr3152), simplify and improve code.

Thanks to rsa for hints.
[12577] Add positive exception for spell 56099
[mr3154] small correct from 12578
SD2 update
[mr3155] Fix Arena problem. close #1429
[mr3156] Improvement group system.
[mr3157] Happy new year guys! good holidays for you! =)
Merge branch 'master' of git://github.com/mangosR2/mangos into testing
tmp fixes