Fix for GH #1821: unexpected table failure
Fix for GH #1821: unexpected table failure

The failure was unexpected because the failure message
reported mixed visual and non-visual column separators
but such were not seen. The fix was to properly
detect trailing visual column separators.

Tests have been added for the fix.

Additional changes:

+ turn off unsolicited warnings for tables violating
  best practices (but code just commented out for now)
+ typo fix

MasterDuke17/rakudo,rakudo/rakudo,tbrowder/rakudo,nbrown/rakudo,Gnouc/rakudo,tony-o/rakudo,lucasbuchala/rakudo,lucasbuchala/rakudo,Gnouc/rakudo,tbrowder/rakudo,nbrown/rakudo,rakudo/rakudo,MasterDuke17/rakudo,rakudo/rakudo,labster/rakudo,labster/rakudo,tony-o/rakudo,lucasbuchala/rakudo,rakudo/rakudo,salortiz/rakudo,tbrowder/rakudo,nbrown/rakudo,salortiz/rakudo,softmoth/rakudo,softmoth/rakudo,tbrowder/rakudo,Gnouc/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,salortiz/rakudo,tbrowder/rakudo,tony-o/rakudo,nbrown/rakudo,labster/rakudo,tony-o/rakudo,softmoth/rakudo,Gnouc/rakudo,salortiz/rakudo,labster/rakudo,salortiz/rakudo,lucasbuchala/rakudo,Gnouc/rakudo,MasterDuke17/rakudo,nbrown/rakudo,MasterDuke17/rakudo,rakudo/rakudo,lucasbuchala/rakudo,softmoth/rakudo,rakudo/rakudo,tony-o/rakudo,labster/rakudo,MasterDuke17/rakudo,salortiz/rakudo,tony-o/rakudo,softmoth/rakudo,labster/rakudo,Gnouc/rakudo,nbrown/rakudo