Keep pclaim window open on unpurchased extension

[Jorg]

If one walks from their currently bought pclaim area onto planned(but unpaid for) pclaim area, the window closes. this should change to allow unclaimed areas to keep the pclaim window open, to make it easier to plan larger pclaim expansions

[Hasta]

-1. easily solved by doing it in two (or multiple if you're feeling ghengis-khaney) iterations of expansion.