Export mapping of single files to merged tables

[Michele Peresano]

Each time submit_jobs.py is run from a grid.yaml configuration file which has n_file_per_job > 1 the resulting output file is a table merged from single files output tables.

The current output filename is composed by the first and last run numbers, but the list of runs which make the merged table is lost.

submit_jobs.py can just export a text table in some format as e.g.,

merged table name	list of simtel runs
TRAINING_energy_gamma_tail_run108-run140.h5	108
	120
	140