Show overflow from allies
Updated changelog storage/overflow
Show storage information in team

* There's now storage information in score overlay
* Show in score if someone is ally / foe (red / green)
* Refactored the code to use own economy sync function
Show overflow of allies in score

It does this by switching value between storage / overflow when storage is 100%
Fixed bugs with showing overflow and replays
New UI-option: Team economy
Team economy off by default
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
Trivial checkbox logic cleanup.
Correctly spell 'developers'.
Clarify some tooltip wordings.
Use a RadioButton control for background selection.
Prevent options dialog components from appearing in front of exit dialog.
Remove theme switching buttons. The theme switching does not exist yet: create a feature branch for this work and add the buttons there. Don't ship buttons that do nothing!
Localise various lobby strings.