These two blocks were not doing the same shade-oriented math as
`setPenShadeToNumber`: effectively these blocks were using the new color
model instead of Scratch 2.0's hue-shade model. This change pulls the
hue-shade color update logic into a separate function, now called by all
the legacy pen blocks.
* localize the block and menu strings in the pen extension
* adds .tx/config to be able to push translations to transifex
* includes format-message to localize strings and extracting them.
* add setLocale function to VM to allow GUI to pass in locale data.
* refresh block definitions when the locale changes.
### Still to be decided
For now just extracting messages from the pen extension into their own file. We’ll need to decide if each category gets its own file, or group all the strings into one resource.
* Move drums into their own folder
* Load instrument samples
* Play notes
* Concurrency limit is shared across drums and instruments
* Increase MIDI note range
* Set instrument directly on musicState object
* JSDoc
* Clean up the play note functions and add comments
* Cleanup
* Check for audioEngine in playDrumNum
* JSDoc and comments
* Round the instrument number
* Fix unit test for set instrument
* Comment fixes
* Nit (condense onto single line)
