Merge pull request #1517 from mbebenita/avx

Some more command line options for the shell.
Merge pull request #1518 from mbebenita/avx

Use a seperate dirty flag for clip depth.
Fix font scaling
Revert flipping of font coordinates
Don't animate if clip depths are different
Merge pull request #1519 from tobytailor/nat

Misc fixes
Collect counters and write them to the console every certain number of frames.
Speed up |dispatchEvent| by doing a quick test to see if any event listeners are registered along the path to the root of the display list.
Add back reference counting code but leave it disabled for now until we fix all the bugs.
Make pause button behave more like paint.
Coerce depth values to integers.
Remove leftover call to removeReference.
Make sure clip values are getting updated
Merge branch 'nat' of https://github.com/mozilla/shumway into avx
Update demo SWF.