Ongoing work on the delta combiner (issue #531).
Ongoing work on the delta combiner (issue #531).

* compose_delta.c: Fix bug in range list handling -- target ranges must
refer to the correct offset in the target stream.
(range_list_node_t): Add member target_offset, rearrange members.
(alloc_range_list): New parameter target_offset, rearrange params.
(build_range_list): Pass correct target offset to build_range_list.
(svn_txdelta__compose_windows): Use target_offset when generating
svn_txdelta_target ops from a range list.

Also various doc changes.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion