Add Var.varlevelup to code. More parser cleanup.

src/backend/commands/recipe.c

src/backend/nodes/copyfuncs.c

src/backend/nodes/equalfuncs.c

src/backend/nodes/makefuncs.c

src/backend/nodes/outfuncs.c

src/backend/nodes/readfuncs.c

src/backend/optimizer/plan/createplan.c

src/backend/optimizer/plan/initsplan.c

src/backend/optimizer/plan/planmain.c

src/backend/optimizer/plan/setrefs.c

src/backend/optimizer/prep/preptlist.c

src/backend/optimizer/util/clauses.c

src/backend/optimizer/util/tlist.c

src/backend/optimizer/util/var.c

src/backend/parser/README

src/backend/parser/analyze.c

src/backend/parser/parse_clause.c

src/backend/parser/parse_expr.c

src/backend/parser/parse_func.c

src/backend/parser/parse_node.c