Some rework on variables

Good bunch of changes

Don't try to read expressions as statements. That yields nothing useful and inevidently bombs out anyway.

Fixed: parser allowed command calls with one too few arguments

- Fixed error display - peeking was pushing recorded `cursor` position out of sync

renamed to undefined labels, not unmarked labels...

goto is now allowed to reference labels that will get defined afterwards.

(0) -30 -10 -7 +7 +10 +30 tip

mercurial