mkdirIfNeeded
utils.mkdirIfNeeded
build the weighted matrix also for the ss ewk regions

Details:
- expand the SignalRegions enum
- expand the 'interesting region' filter
- adjust legend and labels
buildWeightedMatrix.py : fix enum and avoid name mapping
avoid enum conflict after renaming
SusySelectionMatt: make sel methods static
MeasureFakeRate2: sf::ControlRegion -> susy::fake::Region
crashing with new impl
move FakeRegions to SusyMatric
susy::wh::plotregions
add the SsEwk regions to PlotRegion, MatrixPrediction, and SusyPlotter