Add special lines

Add trigger lines based on ODIN beam-crossing type or event type, or number of velo tracks. All lines are currently post-scaled to the permille level. RunHlt, PrepareDecisions, RunPostscale and RateChecker all updated to run over SpecialLines in addition to OneTrackLines and TwoTrackLines. Unlike track-based lines, all SpecialLines will have a single decision per event based only on event-level information (currently ODIN-bank fields and the number of velo tracks). These event-level fields could also be trivially added to OneTrack and TwoTrack line decisions to allow for, e.g. low/high-mult lines.