Allow excluding options from default verbosity

For example I have removed the context by doing:
`verbose=blank,header,footnote,label,new-id,affected,edit,special,project,sync,unwait`
but this is not as nice as something like:
`verbose_exclude=context`
Because it keeps the other default settings intact in case in the feature things are displayed differently.

https://taskwarrior.org/docs/verbosity/