Rename brush-cloneable? to brush-mutable?
Add fun strings procedures to gigls.
Add preliminary code for help system.
Add new brush stuff to gigls/unsafe.
Add blank version of docs.rkt, which will be used by the help system.
Changed default for preserving context.
Add context-cleanup-brushes\!
Add support for brush sizes to turtles.  Add turtle-{x,y,direction}.