This is a followup to #3127. At the time, SPDX licenses were pending approval by Google.
Near complete rewrite of colour picker for Blockly Factory. * Drop IE6 support. * Flip picker as needed so it doesn’t go offscreen. * Add support for no colour. * Factor CSS out of JS. * Provide palette of our standard colours.
Improves UI, but is still pretty clunky. For example there’s still not way to choose “no colour”. Closes #668.
