Split cli messages to case with invalid usage and help message

[nappex]

fix #240

One would be help message

another perhaps usage message for invalid usage of onifumo

This PR is done above the PR #238, because it is nature continuation of it.

Before merging this to master must be ensured merge of #238 to #242

[nappex]

Revise tests! 😈

[nappex]

--help must be used as only one cli argument to run correctly, we do not want behaviour as "rule them all" by help switch as proposed in PR #244 .
If someone use --help with other argument or switch, then it could evoke to user it should output help for certain argument resp. switch. We do not want to implement this feature currently, maybe later. So --help should be used only for general help message for whole Onigumo not for its individual commands.

[Glutexo]

The -h/--help is introduced in a separate pull request #238. This pull request should only introduce the help message.