refactor($parse): remove dead code

[jbedard]

These operators appear to have never actually been supported. This will have one minor side effect where parsing expressions containing ^ and & operators will now throw from the lexer ($parse/lexerr) instead of parser ($parse/syntax).

[lgalfaso]

this is a breaking change and should be presented as such

[jbedard]

The change in error codes would essentially only be seen if someone has a typo in their expression. That counts as breaking? :(

[lgalfaso]

ah, you are right. Misread the patch

LGTM

[tbosch]

Thanks!