USB: Added support for adding 1 new USB memory device at runtime including a callback for mounting it...

Signed-off-by: Swizzy <swizzy@hotmail.co.uk>
Merge github.com:Free60Project/libxenon into Swizzy
iso9660: Fixed hitachi freeze and DVD Mount error... magical!

Signed-off-by: Swizzy <swizzy@hotmail.co.uk>