RLangPApplet: Support static mode

[gaocegege]

Close #51

Signed-off-by: Ce Gao ce.gao@outlook.com

[jeremydouglass]

This is great! Good static sketch support is a huge accomplishment -- it will really help new learners!

Good job also cleaning up the documentation.

It might be worth adding a basic StaticSketch demo as one of the example sketches. Anything that calls size() in a static sketch and then uses width and height.

size(250,150)
background(255,192,192);
line(0, 0, width, height/2)
line(0, 0, width/2, height)
ellipse(width-60,height-60,100,100)

[gaocegege]

Add the example in 85d4e94