Relinquish -v and -h if the user wants them

[DannyBen]

• Add -v as a short code to --version
• Allow the user to hijack -v and -h for their need. If used as a short code for any of the flags, then they will not be used internally for --version / --help.
• Remove version_flag and help_flag from the strings configuration, not sure why they were there in the first place.
• Fix some printf error when printing the flag_requires_an_argument string - since it will always start with -- which confuses printf.