add option to suppress banner

[derkommutator]

Adds a command line option to suppress the top banner. Useful for instance for small displays.

resolves #278

[raboof]

sounds good. I could imagine some people also wanting to suppress the PID USER .. and TOTAL line, but that can perhaps be a future feature when passing multiple -q.

I wonder if the expressions become easier to read when we introduce some more naming (like headerheight = 1 for the PID USER PROGRAM header) and ordering them 'top-to-bottom'?

[derkommutator]

Perhaps. I don't claim to have any real skill in producing tidy code. :) Nor much experience with ncurses, to know standard practices for organising code. I'm just in a similar situation as the OP for #278 and seeing that it was fairly simple to add the option, and nobody else had submitted a PR, did it. :D