Change colour on math_on_list to match Math blocks. Add comment.
Change colour on math_on_list to match Math blocks. Add comment.

git-svn-id: 5890ca18e72b21e319770deb79a4bf5251fa1316@58 564c4054-8e92-c1d3-c2f1-8eb89f0f2216

derrell/Blockly,derrell/Blockly