Remove all time travel stuff. Small parser cleanup.

src/backend/access/gist/gist.c

src/backend/access/hash/hash.c

src/backend/access/heap/heapam.c

src/backend/access/index/istrat.c

src/backend/access/nbtree/nbtinsert.c

src/backend/access/nbtree/nbtree.c

src/backend/access/rtree/rtree.c

src/backend/bootstrap/bootstrap.c

src/backend/catalog/heap.c

src/backend/catalog/index.c

src/backend/catalog/indexing.c

src/backend/catalog/pg_operator.c

src/backend/catalog/pg_type.c

src/backend/commands/async.c

src/backend/commands/cluster.c

src/backend/commands/command.c

src/backend/commands/copy.c

src/backend/commands/proclang.c

src/backend/commands/purge.c

src/backend/commands/recipe.c