This is adding support to handle garrisoned entities defined in map
files by game engine and atlas allowing future extension for atlas ui
and solving recreation of entites on init in D1958. Also solving
deepfreeze described in D2562.
Differential Revision; https://code.wildfiregames.com/D2597
Ticket: #3008
Patch by: Freagarach
Comments by: elexis
This was SVN commit r23529.