building placement WIP : need to place it now and check for tiles under
	modified:   LibreSTR/GameState.cpp
	modified:   LibreSTR/GameState.h
	modified:   LibreSTR/gui/UnitInfoPanel.cpp
	modified:   LibreSTR/gui/UnitInfoPanel.h
	modified:   LibreSTR/maps/PlayerMap.cpp
	modified:   LibreSTR/units/BuildingIdentity.cpp
	modified:   LibreSTR/units/BuildingIdentity.h
	modified:   assets/base_building.res
	new file:   assets/base_icon.png