Stop writing CLI validation. Parse it right the first time

Exactly the opposite of this. We should parse the command-line using _no_ strict types. Not even integers. Nothing beyond parsing its structure, e.g. which option names get which (string) values, and which flags are enabled. This can be done without knowing _anything_ about the application domain, and provide a generic options structure which is no longer a sequence of characters.

This approach IMNSHO is much cleaner than the intrication of cmdline parser libraries with application logic and application-domain-related types.

Then one can specify validation logic declaratively, and apply it generically.

This has the added benefit - for compiled rather than interpreted library - of not having to recompile the CLI parsing library for each different app and each different definition of options.