More efficient use of the charts space  - By JackRainy

By SomeTroglodyte:
- Allow image overlay and changing world wrap in map editor
- Reapply 'city focus' on yield changes
- Upgrading from Unit overview improved

Remove "does not support server feature set" error for uncivserver.xyz

Trigger resource recalculation upon gaining a unit that requires resources

Guard against '><' text causing translation recursion

Badly configured era conditional no longer causes crashes