* New widget div functions, used in context menu code
* Make all widget div positioning functions use the same argument order
* Use new widget div functions for fields
* share code for measuring menu size
* Get rid of positionMenu
* Update copyright date
* Rebuild blockly_uncompressed because there's a new require in town
* Test for widget div math
Text block now uses the extension "text_quotes", supported by Blockly.Constants.Text.QUOTE_IMAGE_MIXIN.quoteField_(fieldName), so that each platform can use the best platform appropriate image (size, density, etc.) for the quotes.
* Beginnings of a JSON block definition unit test set.
* Dispose of unit test workspaces and blocks in finally blocks.
* Clarify JSON error message by echoing arg notation.
Adding support for extensions, functions that can assist with loading blocks, much like init functions, but that can be referenced from JSON definitions. This allows JSON definitions to define dynamic blocks such as onchange handlers and mutators.
Rewrote math_number as an example pure JSON block.
FieldNumber and FieldAngle previously accepted "undefined" as values, if not defined in JSON. This catches these and uses "0" for any NaN value. The constructor value parameter is now optional. Includes tests.
