Flash embedded assets

[aduros]

Flash assets are loaded over HTTP, since this is better for large games that are regularly updated (an updated asset only requires that one asset be re-downloaded, instead of the entire game) and for parity with HTML.

It would be cool if there was an option to package all Flash assets into a single SWF that could be distributed to Flash game portals more easily.

Steps to make this happen:

1. Dust off the old Flash AssetPackager tool: https://github.com/aduros/flambe/blob/9ee975596a8d00aeb0b75d36b4c957c326dce41b/tools/packager/src/AssetPackager.hx
2. Modify flambe.py to optionally use it, and pass the asset swf as a -swf-lib.
3. Create FlashEmbeddedAssetPackLoader that loads symbols from the lib instead of over HTTP.

For now, it's possible to build with asset_base="http://your-cdn.com/assets" to host the assets yourself, if you're ok with footing the bandwidth.