Refactored oaiarchive and simplified usage.

Running oaiarchive CLI now simply sync the records according to the sets definitions in the OAI Repository admin interface, without having to specify any of the old --add
or --delete options.
Replaced most iterations on lists by operations on intbitset objects for enhanced speed.
Fixed issue with OAI IDs & sets being added several times.
Clearer (and more accurate) repository status report.
Status report no longer needs to "run" through BibSched.

Added possibility to get repository status report without running in BibSched environment.