Support customizable Ansi color scheme

[remkop]

Something like Help.setStyle(String, EnumSet<Ansi.Style>).

TBD add method on CommandLine?

Where keys are:

• heading
• command
• options
• option-parameters
• positional-parameters

[remkop]

Note that this will not work for custom synopsis. This is static text in the annotation attribute, so it cannot call the Help.Ansi methods. To support colors in the custom synopsis we need to do something like the "render" method that Jansi offers: "@|red Hello|@ @|green World|@") .

[remkop]

CommandLine.usage(Object, PrintStream, Help.StyleScheme);

class StyleScheme {
  EnumSet<Help.Ansi.Style> command;
  ...
}