Rewrite of the SL record creation code.
Rewrite of the SL record creation code.

This should allow us to deal with split components
and split SL records much more nicely.

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

clalancette/pycdlib,clalancette/pyiso