postprocess can now return Parser.fail
postprocess can now return Parser.fail

when a rule completes, the post processor may now provide a semantic
pass/fail to provide the last word on if the completed rule was a
successful parse

jcorbin/nearley,jcorbin/nearley,Hardmath123/nearley,Hardmath123/nearley,tjvr/nearley,jcorbin/nearley,tjvr/nearley