Fixed unhappiness effect when at 0 happiness

Allow BaseUnit unique functions to return UnitType uniques

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

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

fix light/dark mode tooltip in the wiki  - By alexban011