[#42911737] Create a mejs command-line build script that uses the free Flex SDK to build flashmediaelement.swf

[#43518335] Recreate SWC using Flash Pro CS6, Rebuild SWF using Flex SDK 4.6

[#43518335] Fix all Flex compiler warnings (see build.sh for comments)
Create a global FlashMediaElementDisplay symbol that includes all the objects on the stage in the FLA file.
Expose the FlashMediaElementDisplay symbol to ActionScript.
Instantiate the FlashMediaElementDisplay object and add it to the stage in the FlashMediaElement class.