Command line argument naming should follow UNIX conventions

[mjuric]

Unix programs these days typically follow the GNU conventions for command line arguments. We deviate from them in two ways:

• Have short arguments with more than one character (e.g. -cp in sorcha run). This is ambiguous with shortening -c -p as -cp (see the second bullet here), and makes argparse disable this feature entirely.
• Have long arguments with underscores (_). This goes against GNU conventions (quote: "Long options consist of -- followed by a name made of alphanumeric characters and dashes."), but more importantly it makes our code feel a bit unnatural (very Java-ish). E.g., run git add --help or ls --help (on linux) to see the difference.

I propose we fix this now, before the cmdline API is frozen for v1.0 -- it will be very hard (impossible) to change later. The fix is easy (I'm volunteering to do it).

[mjuric]

Current WIP prototype (early comments welcome):

[mschwamb]

command line argument --help needs to show what parameters are required and which are optional

[astronomerritt]

After some discussion, we'd be happy to implement these changes to the command line arguments -- and only these, in a single dedicated PR -- with the following changes:

• Arguments should be organised into optional and non-optional, as they are now.
• I don't think there should be any defaults for the non-optional arguments. At the moment, there are default file names showing for the input file arguments.
• We're not using --colors. --physical-parameters please. It matches with --complex-physical-parameters.
• Likewise change the description of that argument to "Catalog of object physical parameters".
• The description of --complex-physical-parameters should be "Catalog of object complex physical parameters."
• The description of --verbose should specify "Print additional information to log while running"