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.

animated_gif example bug fixes & changes

1.0.10

animated_gif example bugfixes & changes

doublebuffer example renamed to doublebuffer_scrolltext

Some extra comments about scrolling text added

Move color565() from examples into Adafruit_Protomatter class

1.0.8

Move color565() from examples into Adafruit_Protomatter (not core)

Single pixeldust example

Didn't need two examples for two matrix sizes, it’s just a one-line edit (now commented). Otherwise, code between the two would inevitably diverge and become a support liability. Default size is 64x32.

Examples cleaned up

Lots more helpful comments. "protomatter" example has been renamed "simple" to better convey that one's a starting point.

Restructure code, add animated_gif example

Add animated_gif example (requires TinyUSB-capable board and AnimatedGIF library).

No functional changes, but library code has been rearranged for the contemporary Arduino library layout (using “src” folder, with device-specific headers split up in an “arch” subdirectory), adopt use of “#pragma once” rather than oldschool include guards, other minor housekeeping.

Added a couple Pixel Dust demos

For guides or whomever wants to use them.

Initial Teensy 4.0/4.1 support

Could be better (see “roadmap” issue), but it’s a start!

1.0.2 - Add to GitHub actions

Merge pull request #9 from adafruit/actionsci

Switch to Actions CI