Show error for author when create option with invalid flags

[shadowspawn]

The option parsing is quite loose. This means authors do not get feedback they are using unsupported flags when creating options.

In particular could throw an error for:

• more than two flags
  • helpOption does not support more than 2 flags #1862
  • [Feature request] More than 2 flags per option / case-insensitive flags #2222)
• short flag with more than 1 character
  • Deprecate multi-character short flags #1718
  • Bug in regex for lone short flag #2227
  • Short option name with single character or multiple characters have different result  #2211