Merge pull request #1474 from tschneidereit/nat

Change `grunt avm1` and `grunt flash` to also build the relevant .abc files
Merge pull request #1475 from tschneidereit/nat

Change AVM1's ifFrameLoaded function to not return false forever if the requested frame is > totalFrames
Clipping fix. In Flash, masks that clip nothing should not be visible. In the GFX backend, there was no way to express "clip nothing". This patch fixes that.
Merge pull request #1476 from mbebenita/nat

Clipping Fixes
Merge branch 'nat' of https://github.com/mozilla/shumway into nat
Factor out describeTypeJSON.
Patch forward referenced multinames in TypeNames.
Dispatch events if the child is on the stage, not if the loader is on the stage.
Comment out special glyphCount handling for swfVersions <= 6 since I've ran into swfVersion 6 content that doesn't follow this behavior.
Merge pull request #1477 from mbebenita/nat

Grab Bag
Implement support for AVM1 button actions

All except for dragOver/Out. Those are *annoying*.