Reverse function. Closes #94.

builtin.c

@@ -562,6 +562,7 @@ static const char* const jq_builtins[] = {
   "def to_entries: [keys[] as $k | {key: $k, value: .[$k]}];",
   "def from_entries: map({(.key): .value}) | add;",
   "def with_entries(f): to_entries | map(f) | from_entries;",
+  "def reverse: [.[length - 1 - range(0;length)]];",
 };