Allow Testable to impersonate discord6
Allow Testable to impersonate discord6

Testable.new takes a :$discord named argument that makes it behave like
discord6 in that:

  - it switches its nick to ‘discord6’,
  - sends messages as ‘<testable> $original-message’.

perl6/whateverable,MasterDuke17/whateverable,perl6/whateverable,perl6/whateverable