Enable station upgrading

Enable to upgrade a starbase or an outpost to the currently best
buildable version.
change CSector::m_bIsStationBuild to a std::map

Allows to correctly display station work information.
savegames incompatible
Merge branch 'upgrade_station'

Waiting further makes additional conflicts a lot more likely.

Conflicts:
	BotE Game/trunk/Source/GUI/ShipBottomView.cpp