Support for Arduino Uno R4

Library will now compile and run for the variants of the Arduino Uno R4 with the Renesas microcontroller.

Fixed Example Code

Arduino compiler settings such that floating point version of max() was not selected during compilation. This change fixes that. Also incorporates a few other tweaks.

Support for Teensy 4.x

This releases adds support for Teensy 4.x boards, plus addresses a few compiler warnings.

Update to GFX v1.9.0

Update to leverage new features in Adafruit GFX v1.9.0 library release.

v0.9.0

First public release.