Add diagrams for a bunch more canvas stuff (#198)

* Add clip diagrams

* Add diagrams for drawLine / rect

* Add diagrams for oval / circle

* Background

* Background

* Fix repaint

* Better diagram for Rect.fromCircle

* A bunch more diagrams

* Radius diagrams

* Make stuff private

* Clean up constants

* Regenerate

* Regenerate

* Remove abbreviation

* New color scheme

* Regenerate

Author: pingbird