Minor tweaks to cmdline.h to better suit my usage
Minor tweaks to cmdline.h to better suit my usage

* Descriptions for readers, for better error reporting and usage help.
  This also allows these descriptions to be multiline, and they're
  indented correctly.
* A bit better formatting of options and defaults.
* Print full list of errors when there are more than one.
* #undef max
* Header as well as footer on single-line command help.
* Remove parse and parse_check variants I don't use.
* Allow processing without looking at argv[0].
* Optionally stop the processing at the first non-command, so that
  you can have a program and its arguments without trying to parse
  the arguments themselves.

Velro/renderdoc,Zorro666/renderdoc,Yours3lf/renderdoc,Yours3lf/renderdoc,adrianbu/renderdoc,Lssikkes/renderdoc,Velro/renderdoc,michaelrgb/renderdoc,adrianbu/renderdoc,adrianbu/renderdoc,etnlGD/renderdoc,victor-moya/renderdoc,Yours3lf/renderdoc,moradin/renderdoc,googlestadia/renderdoc,adrianbu/renderdoc,victor-moya/renderdoc,moradin/renderdoc,baldurk/renderdoc,googlestadia/renderdoc,Anteru/renderdoc,Lssikkes/renderdoc,etnlGD/renderdoc,TurtleRockStudios/renderdoc_public,Velro/renderdoc,etnlGD/renderdoc,baldurk/renderdoc,cgmb/renderdoc,Yours3lf/renderdoc,moradin/renderdoc,Zorro666/renderdoc,cgmb/renderdoc,googlestadia/renderdoc,moradin/renderdoc,etnlGD/renderdoc,baldurk/renderdoc,Zorro666/renderdoc,Yours3lf/renderdoc,googlestadia/renderdoc,Velro/renderdoc,Yours3lf/renderdoc,TurtleRockStudios/renderdoc_public,michaelrgb/renderdoc,Lssikkes/renderdoc,Velro/renderdoc,TurtleRockStudios/renderdoc_public,googlestadia/renderdoc,Anteru/renderdoc,Zorro666/renderdoc,Zorro666/renderdoc,Anteru/renderdoc,baldurk/renderdoc,victor-moya/renderdoc,victor-moya/renderdoc,Lssikkes/renderdoc,cgmb/renderdoc,baldurk/renderdoc,Anteru/renderdoc,victor-moya/renderdoc,cgmb/renderdoc,moradin/renderdoc,Lssikkes/renderdoc,etnlGD/renderdoc,Anteru/renderdoc,michaelrgb/renderdoc,adrianbu/renderdoc,TurtleRockStudios/renderdoc_public,googlestadia/renderdoc,baldurk/renderdoc,michaelrgb/renderdoc,Velro/renderdoc,michaelrgb/renderdoc,Lssikkes/renderdoc,Zorro666/renderdoc,cgmb/renderdoc,etnlGD/renderdoc,Anteru/renderdoc,victor-moya/renderdoc,adrianbu/renderdoc,TurtleRockStudios/renderdoc_public,TurtleRockStudios/renderdoc_public,moradin/renderdoc,Anteru/renderdoc