the note about historical versions also being covered wasn't strictly
needed and was ugly. the LICENCE being in the root file from the very
first commit is sufficient.
- added support for placeholder labels
- improved error messages
- better help command
o debugger
- command template is now labelled
o test
- corrected "expect success" message
- added Writer type. used for comparing buffered output with
example strings
- used by modalflag and symbols test package, although it may be
used by other packages in the future
- added ExpectedSuccess() and ExpectedFailure() functions
