Fix item purchasing, image loading
Fix item purchasing, image loading

Recalculate what items are affordable on purchase attempt, rather than
based on load. Also load item images more reliably.

kidaa/codecombat,codecombat/codecombat,icodegame/codecombat,VilkkuV/codecombat,javatlacati/codecombat,Zerrien/codecombat,fabichoi/codecombat,icodegame/codecombat,fabichoi/codecombat,javatlacati/codecombat,codecombat/codecombat,javatlacati/codecombat,fabichoi/codecombat,icodegame/codecombat,javatlacati/codecombat,fabichoi/codecombat,Zerrien/codecombat,codecombat/codecombat,Zerrien/codecombat,probil/codecombat,icodegame/codecombat,kidaa/codecombat,jeremiahyan/codecombat,VilkkuV/codecombat,probil/codecombat,probil/codecombat,Zerrien/codecombat,jeremiahyan/codecombat,kidaa/codecombat,codecombat/codecombat,probil/codecombat,codecombat/codecombat,kidaa/codecombat,jeremiahyan/codecombat,VilkkuV/codecombat,VilkkuV/codecombat,jeremiahyan/codecombat,javatlacati/codecombat