Return when there are no input files

[jmcarcell]

BEGINRELEASENOTES

• Return when there are no input files to allow using -h

ENDRELEASENOTES

Fix #474

Do you want to try it out @Victor-Schwan?

For me:

k4run ILDReconstruction.py -h
[k4run - INFO] io_helpers.finalize_converters: Added an input converter (EDM4hep to LCIO) to the MyAIDAProcessor algorithm
[k4run - INFO] io_helpers.finalize_converters: Added an output converter (LCIO to EDM4hep) to the CollPatcherREC algorithm
usage: k4run [--dry-run] [-n NUM_EVENTS] [-l] [--gdb] [--interactive-root] [--log-level {VERBOSE,DEBUG,INFO,WARNING,ERROR}] [-i] [--compactFile COMPACTFILE |
             --detectorModel {ILD_l5_o1_v02,ILD_l2_v02,ILD_l4_o1_v02,ILD_l4_o2_v02,ILD_l5_o1_v03,ILD_l5_o1_v04,ILD_l5_o1_v05,ILD_l5_o1_v06,ILD_l5_o2_v02,ILD_l5_o3_v02,ILD_l5_o4_v02,ILD_s2_v02,ILD_s4_o1_v02,ILD_s4_o2_v02,ILD_s5_o1_v02,ILD_s5_o1_v03,ILD_s5_o1_v04,ILD_s5_o1_v05,ILD_s5_o1_v06,ILD_s5_o2_v02,ILD_s5_o3_v02,ILD_s5_o4_v02,ILD_l5_o1_v09,ILD_l5_v11,ILD_FCCee_v01,ILD_FCCee_v02}]
             [--runBeamCalReco | --noBeamCalReco] [--inputFiles ['file1', 'file2'] [['file1', 'file2'] ...]] [--outputFileBase OUTPUTFILEBASE] [--lcioOutput {off,on,only}]
             [--cmsEnergy {91,160,240,250,350,365,500,1000}] [--perfectPFA] [--runOverlay] [--beamCalCalibFactor BEAMCALCALIBFACTOR] [--trackingOnly]
             [--MySiliconTracking_MarlinTrk.OutputLevel
...

It prints the options twice, once in this short version and another one with also a description when available.

[jmcarcell]

Merging so that it can be tested in the nightlies. It worked for me locally.