Add tiling support

This is a partially breaking change.
At the C level, definitely breaking: the _PM_init() function REQUIRES an extra argument for tiling, and this is inserted BEFORE the void *timer arg.
At the C++ level, potentially but rarely breaking: the Adafruit_Protomatter constructor likewise accepts an extra argument in a similar position, but with defaults assigned for this and the timer arg, it'll rarely be encountered, UNLESS someone was using the timer arg (super exceedingly rare). I put them in this order because tiling seems more likely than ever using the alt timer functionality.