Bug 794152 - JPEG 2000 Code Stream .j2c support.
Current OpenJPEG code only supported the base JP2 container. It now supports also the JPEG 2000 codestream (which is usually contained inside other formats, like the JP2 container format, but can also sometimes be on its own). The current magics and extension strings were also mixing all kind of formats. This is now cleaned up a bit.