- simplified logic, plus various minor cleanup and modernization
- input of --IFO is now inconsistent with --DataFiles, as giving both
  does nothing useful
- info output total amount of data 'Tdata' instead of 'Tspan' (useless)
- (--minStartTime,--maxStartTime) can now work both as constrains on
  SFT-loading, timestamps-loading, or specify a gapless duration if
  neither --DataFiles nor --timestampsFiles is given
- adapted tests to new input logic