Prompt user for input

This PR won't deal with hidden stuff like passwords yet.

First have to deal with that synopsis parser unsets the key so I can't even do a check on it.
New flavour "prompt" by using `( )` instead of the optional `[ ]`. 
Please check the whole `gen_patterns` maybe I am overkilling the aditions.

A. No password, no prompt
`wp core config --dbname=foo --dbuser=ano`
B. Password flag, prompt
`wp core config --dbname=foo --dbuser=ano --dbpass`
C. Password assoc arg, no prompt
`wp core config --dbname=foo --dbuser=ano --dbpass="secret"`


[ ] Implement prompt
[ ] Prompt wp core config
[ ] Prompt wp core install
[ ] More prompts?