Initial scenario/dev console!

By SomeTroglodyte:
- Map overlay toggle buttons rework
- Add a map import tool able to read "Battle for Wesnoth" maps

Fix free buildings triggering from conditionals in incorrect places  - By SeventhM

Add a setting to forbid closing popups by clicking behind them  - By karmaBonfire

[Translation] Add back "general" unit types  - By Ouaz