Selections need an overhaul

[ebernerd]

Selections in their current state are broken and almost unuseable, especially across network play.

• [ ] Selections need to work across networks
• [x] Rewrite selections so that objects within a selection are contained differently
• [x] Cards within a selection should be deleted when the root of a selection is hovered over the delete charm

I suggest writing selections to use the unique network ids rather than the odd packing system we have now; that way the draw order and everything else is kept the same.

[ebernerd]

As of early-afternoon 5.9.2017, selections now work much better, and deletion works as expected. Decks cannot be shuffled or split if they are the root of the selection; only the trash icon appears.

Network selection will be implemented soon, along with user colors and highlighting a user's selection using their color across network play.