greg: more 0.4.5 updates

remove G from YY_ERROR and YY_INPUT 1st arg
enclose user actions in braces to allow local variables to be declared in C89
use C89 escape for ESC
replace errblock impl with upstream
use the upstream peg error Action block feature,
    get rid of the added errblock field from every node.
    add erract sample and testcase
improve Predicate layout
update Query from peg: use readable names
improve yyinit(&g): memset(0), not memcpy malloced g
add define/undef helpers, use p2 YY_SET helper