Add masking support to 2D backend.
Merge branch 'nat' of https://github.com/mozilla/shumway into nat
Add some source files to packages instead of having them manually added to embeddings
Merge pull request #1364 from tschneidereit/nat

Add some source files to packages instead of having them manually added to embeddings
Make shell unit testing harness work again
Adapt graphics unit tests to serialization format changes
Add getter for Stage#alpha

Stage overrides tha `alpha` setter. Unfortunately, not specifying a getter in the same child class that overrides a setter leaves the getter undefined ...
Fix Stage unit tests

Some fixes for correctness issues in the tests themselves, plus changed all `check` calls to equivalent `eq` calls.
Turn failing bitmap unit test into warning

All active tests should be green.
Fix shell unit testing harness

Also adds the ability to run test file collection files, used in the next patch.
Run shell unit tests after all relevant build targets

This introduces a unit tests collection file `shell-tests.js` and runs it each time one of the `swf`, `flash`, or `player` build targets is invoked.

Don't regress these tests from hereon out!
Merge pull request #1365 from tschneidereit/nat

Automated shell unit testing
Store lineStyle's thickness as twips in coordinates

Turns out the thickness isn't rounded to the nearest pixel after all, but stored - and interpreted - in twips. Because the commands buffer is in bytes, the thickness is written into the coordinates instead. In some ways this is even less dirty than the previous solution. It wastes two bytes, but line styles aren't set that frequently, so this is fine.
Emit endFill/endLine commands at the end of a shape path

Otherwise, we'll happily continue playing back path commands for the last fill in the renderer while line paths are played back, and only apply the fill once all paths are complete.
Don't auto-close strokes

For fills, we have to manually draw a line connecting the first and the last coordinates of the path. For shapes, not so much.
Store shape fill gradients' focalPoint as fixed8 instead of byte

Turns out these can have fractional parts.
Merge pull request #1366 from tschneidereit/nat

Shape fixes
Compiles the extensions
Merge branch 'nat' of github.com:mozilla/shumway into nat
Remove usage of arrow functions from shell unit test runner

Because old shells.