get basic gameplay in place

This implements movement, a draw pile, discard pile, hand. The ability
to play cards, rudimentary card effects, enemies, time passing or not.

There's of course a long way to go here, even in the basic gameplay

The player needs health, there needs to be indicators for what is
going on to make everything less confusing. Cards need descriptions
and to be much clearer in general. Enemies need to drop loot, the
player needs a deck management screen and an inventory. The list goes
on! But the list is shorter than it was.
initial commit