DKS - updated test to reflect current "Function layers" documentation: http://calebevans.me/projects/jcanvas/docs.php?p=layers#function-layers
DKS - new tests that demonstrate jCanvas' new feature of automatic redraw after removeLayer()
Merge branch 'master' of https://github.com/caleb531/jcanvas
Merge pull request #69 from dksmiffs/master

(resubmit) new unit tests that exercise auto-redraw features of 39fec4b