renderer2: division by zero failsafe, refs #688
mod: integer division casting
mod: sync MG/MG_SET cooling fixes #687
Merge branch 'master' of https://github.com/etlegacy/etlegacy.git
mod: casting optimization
renderer2: better division by zero check, refs #688
ui: messages for early return in UI_LoadCampaignsFromFile
ui: dirlist buffer increased fixes #638, show levelshot instead of
campaign info for NON camaign game types, messages for early return
mod: prevent apply/invite/propose to full fireteam, cleanup
misc: ui code cleanup part 1 out of 2