EditCampaignActivity: support map-based entry

[kuhrusty]

Instead of entering stuff in a form which looks like the record sheet on p. 34, it would be fun to have a picture of the map, and you just tap on locations to set the danger level & map traits.

(This would also let you save Explored tokens for roads & paths; the rules say you don't save those, but I think that's just because it would have complicated the p. 34 record sheet. In order to do that, you'll need to modify the CampaignState code.)