document and deprecate colorCalculator
document and deprecate colorCalculator

fixes #1225

dc-js/dc.js,dc-js/dc.js,aaronhoffman/dc.js,mtraynham/dc.js,aaronhoffman/dc.js,mtraynham/dc.js,TheDataShed/dc.js,dc-js/dc.js,dc-js/dc.js,mtraynham/dc.js,TheDataShed/dc.js,TheDataShed/dc.js,aaronhoffman/dc.js,mtraynham/dc.js,dc-js/dc.js,TheDataShed/dc.js,mtraynham/dc.js,aaronhoffman/dc.js,aaronhoffman/dc.js,TheDataShed/dc.js