#101 imgmount CUE+FLAC and MAME CHD support

[eadmaster]

CUE+FLAC already discussed here:
http://www.vogons.org/viewtopic.php?f=31&t=37308&p=328101

MAME CHD v5 is a convenient disk container combining LZMA+FLAC+Deflate compresssion.
I would prefer to use CHDs since they are easier to convert using the chdman tool.