Much better code for supporting SF records.
Much better code for supporting SF records.

This much more closely deals with the differences between
Rock Ridge 1.10 and 1.12 for SF records.  Still no tests
since we have no real-world experience with SF records
to draw on.

Signed-off-by: Chris Lalancette <281cd07d7578d97c83271fbbf2faddb83ab3791c@gmail.com>

clalancette/pyiso,clalancette/pycdlib