Ignore the cvs src tree tarball I use for testing the import

Because committing it would be annoying.
Extract temporary cvsroot from a better location and clean out hooks
Don't autocommit by default, but allow a flag to do so.
Fixup vendor perl, then a separate commit for local patches
Failing logs from vax, but individual testing shows the same as 5.18.2
Add a helper method for adding and removing files from cvs

This lets me make CVS match what is actually in the source directory.

I didn't remove it from bin/import_perl yet as I may want to go the
other direction and make that standalone.
Moved the tarball with cvsroot in it
Adjust patching instructions

This seems to mostly work, although it does not remove empty
directories.