Exit status of a type manager method

A user-defined type manager method must return to cleartool an exit status that indicates how the command is to be completed. The symbolic constants in versionvault-home-dir/lib/mgrs/mgr_info.sh specify all valid exit statuses. For example, an invocation of create_version may create a new data container, and return the exit status MGR_STORE_KEEP_JUST_NEW. If creation of the new data container fails, create_version returns the exit status MGR_STORE_KEEP_JUST_OLD.