Krzysztof Gogolewski authored Jun 17, 2021 and Marge Bot committed Jun 22, 2021

- Remove fstName, sndName, fstIdKey, sndIdKey - no longer used,
  removed from basicKnownKeyNames
- Remove breakpointId, breakpointCondId, opaqueTyCon, unknownTyCon -
  they were used in the old implementation of the GHCi debugger
- Fix typos in comments
- Remove outdated comment in Lint.hs
- Use 'LitRubbish' instead of 'RubbishLit' for consistency
- Remove comment about subkinding - superseded by
  Note [Kind Constraint and kind Type]
- Mention ticket ID in a linear types error message
- Fix formatting in using-warnings.rst and linear-types.rst
- Remove comment about 'Any' in Dynamic.hs - Dynamic
  now uses Typeable + existential instead of Any
- Remove codeGen/should_compile/T13233.hs
  This was added by accident, it is not used and T13233 is already in
  should_fail