fix for
issue #186 ("Screen gets messed up when selecting Hand Drawn Map")
Ok, 20,000 was a bit much. Arbitrary multiplier that seems to shove things off enough.
decouple current theme from map theme (fixes theme confusion bugs of last commit)
MapModel converted to QStandardItemList; separators fixed; changed used data format (human-readable struct instead of magic list) for map info in HwMapContainer (+ various small cleanups in that class)
MapModel, various cleanups. TODO/FIXME: QComboBox separator not working with custom models
messing with the theme model a bit (gets now auto-updated after DLC download too)
Cursor for DrawMapScene. Feel free to ajust its look.
mapContainer: use DataManager, reload maps after data update (e.g. by DLC)