strip: pull core strip logic into its own function

unbundle: accept multiple file arguments update test-bundle for multiple unbundle support

convert: handle new cvsps with Tags: and multiple tags.

cat: return an error on failure

tests: add merge test for changeset 9fe267f77f56 When all the files in a directory are moved somewhere else, and new files are added in changesets of the local branch, a subsequent pull and merge shouldn't rename the locally added files too.

purge: add the clean alias inspired by git-clean and svn-clean