Implement help message structure for single arguments

[Bijaelo]

This is a note for myself while in Development.

Initially the help message can have a static structure, but a more intelligent design would be to used a similar structure to argparse where named elements can be included. The simplest method for doing this, would be to use the glue package. Several R functions are available in this package.

I suggest (to myself) to make a help be stored as a struct with message and print_fun, so the user may supply their own print function as well (if they so desire).