Rename CVSNT "mergepoints" test and make it executable.
- rename test-convert-cvs-builtincvsps-cvsnt-mergepoints
(and related files) to test-convert-cvsnt-mergepoints
- this ensures that the test will be run, but does NOT make
it pass: in particularly, it fails regularly for me due
to the inconsistent behaviour of CVS itself
- expect "Branchpoints:" in debugcvsps output
% directory moved and symlinked
adding foo/a
% now addremove should remove old files
adding bar/a
adding foo
removing foo/a