Support for config file(s)

[readbeyond]

Add support for config file(s) that can hold:

• job/task parameters
• rconf parameters
• other stuff (e.g., auto-update kill switch? exec paths?)

Clearly command line parameters should take precedence over config file(s).

Augment current tools to read a given config file, specified as a command line argument (maybe as the value of -c or --configuration switch).

Put the default (empty? commented out?) config file in the user directory. Need to investigate which is the standard location nowadays (i.e., ~/.aeneas vs ~/.config/aeneas vs ???) and what happens on Windows.

Good candidates for the config file syntax: TOML, JSON.