Fixed India's 'double unhappiness' unique

By SeventhM:
- Fix buildings/units not triggering and golden age stat updates
- Avoid crashes with incorrect condtionals
- Scaling purchase costs for faith/culture/science/etc. with speed
- Better support for lacking a capital

By SomeTroglodyte:
- AI support for Alpha Frontier-like Workers
- Prevent activation of disabled actors via keyboard
- Key shortcuts for Main Menu Screen

Fix civilopedia gold cost  - By Skekdog

Other modding fixes :)