Log Message:
Update to 2.26

Changelog:
2.26: 2013-03-13
     Enable Subversion dump reader to handle yet another pathological case.
     Code has been tested and verified with PyPy.
     Prefer author date for action stamps when it is available.
     More speed tuning.

2.25: 2013-03-07
     More speed tuning in repository analysis.
     O(n**2) cost for renumbering has been eliminated, svn_no_renumber is gone.
     New 'timings' command displays phase timings for repo analysis.
     Improved packaging for distributions (thanks, Mike Swanson).

2.24: 2013-03-03
     Fix a crash bug in the new blob handling, and more performance tweaks.

2.23: 2013-03-01
     Drastically cut the amount of disk storage and I/O required for surgery.
     Add svn_ignore_properties option.
     The .svn extension is now stripped from repo names on load.

2.22: 2013-02-26
     New debranch feature for merging branches that should be subdirectories.
     Minor speed tuning via memoization.

2.21: 2013-02-21
     Added "compressblobs" and "svn_no_renumber" option for \ 
very large repos.
     Added the "sizes" and "lint" commands.
     Interpretation of timezone field in author maps was buggy, is now fixed.
     Experimental Emacs Lisp mode for editing comment mailboxes.

2.20: 2013-02-08
     Teach repodiffer how not to choke on revisions with empty manifests.
     Make repodiffer more explicit when a revision's parent set changes.
     Improvements to the graph command's output of branches.

2.19: 2013-02-06
     Serious tuning of internals for reduced memory usage.

2.18: 2013-02-02
     Translation of symlinks in Subversion repos was buggy, is now fixed.
     repodiffer now has a useful and documented return value.
     New --tree-diff option of repodiffer shows context diffs of mismatches.

2.17: 2013-01-26
     repodiffer can now take a map file and show fossil IDs with diff reports.
     The '?' selection-set modifier can be repeated for effect.

2.16: 2013-01-25
     Fix a memoization bug that resulted in misbehavior after branch cuts.

2.15: 2013-01-22
     Switch to cvs-fast-export for reading RCS and CVS collections.
     Efficiency and code-cleanup improvements by Julien Rivaud.

2.14: 2013-01-19
     Dramatic decrease in memory footprint on large repositories.
     Improvements in DAG visualization via 'graph'.

2.13: 2013-01-08
     The new 'graph' command supports making commit graphs in the DOT language.
     On read of an import stream, interpret a "cvs-revisions" property.