When a highlighter is used instead of a cursor it looks much better when
all the options have the same length. With right_pad_options all options
are right-padded with spaces so they have the same length. Also, an
example for a cursorless menu is added.
The _style is redundant, as the whole theme is a collection of styles.
Headers are not really regarded as headers, more as text. Highlight
makes more sense as highlighted.
This is an API breaking change.
The select/unselect icons of a CliMultiMenu will in nearly all cases be
changed together, therefore it makes sense to let the API be less
verbose for this case.
This is an API breaking change for CliMultiMenu