Refunding Slade's Upgrades#155

Simple idea: When Slade opens up the menu for the upgrade shop from his chest, selecting an upgrade he already has will refund half of the upgrade’s cost in exchange for making him lose the upgrade. This would allow him to immediately gain coins to pull items, while losing and having to rebuy the chosen upgrade would be a meaningful drawback. I think item play is awesome, and Slade does scratch that itch for me, but this should make his ability to access items at least a little better. Also, more options are always nice.