Add labels and gotos. (Fixes #101)
Try using a table in goto-form.
Lookup labels using a Dict in typeinf.
Use an array instead of a dict to index labels.
Macro hygiene and error messages for gotos.
Remove unecessary interpreter changes.
Make goto play nice with try/catch blocks.
Basic goto tests.
Forbid gotos from finally blocks.
Forbid goto skipping finally blocks.
Remove unused symbolicgoto_sym and symboliclabel_sym globals
Merge pull request #5699 from dcjones/goto

Add labels and gotos. (Fixes #101)