Fakedate: implements parts of Playdate SDK for testing

I wanted to test parts of my game outside of the Simulator, which meant I needed things running under regular Lua, and I wouldn't have access to anything in the SDK which was implemented natively. I didn't need much, mostly some data structures (playdate.geometry,point, playdate.geometry.vector2d) and enough of the clock stuff to fake time passing. So I created fakedate, a library that provides fake-ish implementations of a small part of the Playdate SDK. I want to emphasize how little it currently implements. In terms of raw things implemented, it's about 25%, but much of that is constants, and some of it is "technically new is implemented, but in practice will fail." But some of the geometry structures and clock stuff works for my purposes, and maybe would be useful for yours.