0.15.2.4 Hotfix

[h2]Changelog[/h2]

Improvements:
- Added M1A1 and T-72 formations for use in instant action

Bugfixes:
- Fixed "disable" objectives not completing correctly
- Arena Demo missions objectives are more descriptive

Balance Changes:
- T-80s in Instant Action T-80 formation reduced from 3 groups of 4 to 2 groups of 3.
- Reduced damage of M256 250 -> 200
- Reduced damage of 125mm USSR 275 -> 220