Add the map of SVN revision numbers to changeset ids.

This is mostly to help history-digging, especially when
focussing on feature branches.
Note that not all changesets are in the main repository,
but they are all in the full history repository.

Misc/README

@@ -21,6 +21,7 @@ python-wing*.wpr        Wing IDE project file
 README                  The file you're reading now
 README.valgrind         Information for Valgrind users, see valgrind-python.supp
 RPM                     (Old) tools to build RPMs
+svnmap.txt              Map of old SVN revs and branches to hg changeset ids
 SpecialBuilds.txt       Describes extra symbols you can set for debug builds
 TextMate                A TextMate bundle for Python development
 valgrind-python.supp    Valgrind suppression file, see README.valgrind