Deny option (or something that looks like an option) as option argument.
Add TestOptionAsArgument.
Update code and test based on comments in #112
Mixing raw and interpreted string literals didn't make any sense..
Merge pull request #112 from GeertJohan/master

Deny an option (or something that looks like an option) as flag argument.
Use newErrorf instead of fmt.Sprintf and newError
Merge pull request #113 from GeertJohan/newErrorf

Use newErrorf instead of fmt.Sprintf and newError
Accept any single character arguments including '-'
Added comments and trimmed codes
Merge pull request #114 from shirayu/onechararg

Accept any single character arguments including ``-``
Added empty line for improved readability