Switched to using Adobe as3commons version of PNGEncoder because there
were issues with the other encoder when used on iOS (files could be
opened on the desktop but not decoded by Flash for some reason).
Appears there are some line ending issues between OS X and Windows,

working on setting up git config and .gitattributes to resolve this, but
for now have a couple of files to commit.  A couple of changes in here
for testing out scaling the layerManager and using a halved canvas.