Fixed unhappiness effect when at 0 happiness

All BaseUnit uniques, e.g. Never appears as a Barbarian unit, Limited to [amount] per Civilization, can be placed on unit type

By SeventhM:
- Add unique for increasing price every time it's built
- Fix mistakes with unavailable unique

By SomeTroglodyte:
- Fix Capture when a teleport was necessary
- Tweak Overview Politics Diagram for a defeated player
- Patch AlertPopup to correctly close when it cannot find a required asset