PrChecker functional

Major refactoring of the PrChecker to make it fully functional and thread safe. Current state is the following :

• PrChecker2 has been dropped, replaced with a new PrChecker
• the new PrChecker only deals with one type of tracks
• so the configuration of the different types to be checked has moved to configuration
• and this includes in particular the cuts to be applied
• new Prchecker is functional
• thread safety has not yet been tested

This merge request does not change the physics output but does change the ref files, as indentation and checker names have changed. I did check (using RegexpReplacer in LHCbExclusions.py) that everything is consistent. For the record, here is what I added to it :

    RegexpReplacer(
        orig=r'^VeloPrChecker.Velo  *',
        repl=r'SomePrChecker ') +
    RegexpReplacer(
        orig=r'^PrChecker[^ ]*  *',
        repl=r'SomePrChecker ') +
    RegexpReplacer(
        orig=r'  *',
        repl=r' ') +
    RegexpReplacer(
        orig=r'^[^ ]*MCCheck  *',
        repl=r'SomePrChecker ') +
    RegexpReplacer(
        orig=r'^[^ ]*MC\.\.\. INFO',
        repl=r'SomePrChecker INFO') +

For practical purposes, I've added these lines to BrunelExclusion in Brunel!710 (closed) so that it's easier to validate the changes.