Improvements for gain selection automation

[marialainez]

Main changes that have been made in this PR:

• Write history files for each subrun (apart from the log files) + update them every time the gain selection script is launched
• Allow launching the gain selection script several times without launching the jobs that are already running again (if the history file exists and is empty for a given subrun, it means that the job is running for that run, so it doesn't launch it again)
• Change the check option so that it is done looking at the history files and not at the log files
• Add simulate option to the gain selection script
• Once the gain selection finishes correctly for all runs, the gain selection script is launched with the check option to see if there is any run missing that needs to be copied to R0G.

[morcuended]

some changes in the log messages, to make following the logs easier. I would just leave some log info messages for general actions happening and maybe just give info at run level.