drop channel-specific control regions (validated, see Feb_02 control plots)
SusyPlotter: drop unused isEe/isMm/isOf vars
move increment(n_pass_category) to increment counters (avoid multiple increment with syst)
drop n_pass_muIso, n_pass_elD0Sig counters (now done in SusyNt)
SusySelection::computeSsFlags: move sameSignOrQflip

Details:
moving sameSignOrQflip before all the other 2l stuff. This is where it
should be, and it makes the rest of the code cleaner.
It _does_ change a little bit the cutflow, although only at the initial stages.