rtt: regenerate yyerror.c for Bison parser; document merr and YYUNDEF
rtt: document pinned %token numbers and Bison-generated parser policy
rtt: give thread-local specifiers their own token
runtime: classify passthrough markers
rtt: add host and raw C passthrough
rtt: regenerate bison output for host and raw C passthrough
src/common: resolve quoted #include relative to including file
Fix system() redirect parse: do not treat 2>&1 as >&