Support grouping of options in the help message

[larskuhtz]

The options in the help message should be either automatically grouped according to the structure of the configuration type or an explicit group annotation could be given to the option parser.

• implement support for grouping of options to optparse-applicative
• work with optparse-applicative maintainers to find a solution that is accepted for merge to master
• add support for grouping of options to configuration-tools

[larskuhtz]

Grouping of options in the help message is implemented in the branch optparse-applicative-with-groups.

The branch depends on pcapriotti/optparse-applicative#231. It seems that in it's current form it doesn't have a chance to be integrated into optparse-applicative.