AGS.Native: set loaded game version on 2.72 project import

This lets some data reading routines to know actual format version they are loading. We switch back after game is imported to let drawing routines "see" latest game version.
In general this is indeed a hack, but the AGS.Native code is still such a mess, the proper solution would require to rewrite much of its contents, which is beyond scope of this fix.
Compatibility: < 3.1.1 GetLocationName() return space for nameless object
Linux: changed savedgame path to $XDG_DATA_HOME/ags
Linux: corrected BuildXDGPath()

This corrects previous commit (bb566df6f4f527cf474179dc064cffcf7e95f318) where "ags" subdirectory was appended only if XDG_DATA_HOME enviroment variable is not set.
Fixed crash when trying to auto complete an empty word after a define.
Updated build version (3.3.0.1158)
Merge branch 'master' into develop-3.3.1