Remove 'Xngine' strings.
Fix catastrophic indentation issues in trueskill.lua

Closes #224
Fix custom backgrounds in skirmish/LAN.

Fixes #225
Disable collision on sinking air wrecks

Air wrecks were colliding will other units, sometimes causing them to get
stuck in naval units.

This resulted in scouts having intel so long as they didn't sink to
sea-bottom and get wrecked

Fixes #194, closes #222
Update in-lobby changelog
Fix typo in changelog