* typedef pen and constexpr create_pen for #6
* Prevent out of bounds clip permitting write outside buffer
* camelcase rect, point, and pen types
* added triangle(p1, p2, p3) and polygon(std::vector<Point> points) methods to graphics library
* change all uses of pen that were uint16_t into Pen type
* updated micropython modules to use new rect, point, pen naming
* added line(p1, p2) method to pico graphics library with faster vertical/horizontal special cases
Co-authored-by: Jonathan Williamson <jon@pimoroni.com>