Pass correct fields to evaluate_[after|older]

We are passing the wrong fields into `evaluate_after` and
`evaluate_older`. 'after' is associated with _absolute_ timelocks, this
means 'height'. 'older' is associated with _relative_ timelocks, this
means 'height'.

Author: tcharding

src/interpreter/mod.rs

@@ -605,15 +605,15 @@ where
                 Terminal::After(ref n) => {
                     debug_assert_eq!(node_state.n_evaluated, 0);
                     debug_assert_eq!(node_state.n_satisfied, 0);
-                    let res = self.stack.evaluate_after(n, self.age);
+                    let res = self.stack.evaluate_after(n, self.height);
                     if res.is_some() {
                         return res;
                     }
                 }
                 Terminal::Older(ref n) => {
                     debug_assert_eq!(node_state.n_evaluated, 0);
                     debug_assert_eq!(node_state.n_satisfied, 0);
-                    let res = self.stack.evaluate_older(n, self.height);
+                    let res = self.stack.evaluate_older(n, self.age);
                     if res.is_some() {
                         return res;
                     }

src/interpreter/stack.rs

@@ -232,9 +232,9 @@ impl<'txin> Stack<'txin> {
     pub(super) fn evaluate_after(
         &mut self,
         n: &u32,
-        age: u32,
+        lock_time: u32,
     ) -> Option<Result<SatisfiedConstraint, Error>> {
-        if age >= *n {
+        if lock_time >= *n {
             self.push(Element::Satisfied);
             Some(Ok(SatisfiedConstraint::AbsoluteTimelock { time: *n }))
         } else {
@@ -251,9 +251,9 @@ impl<'txin> Stack<'txin> {
     pub(super) fn evaluate_older(
         &mut self,
         n: &u32,
-        height: u32,
+        age: u32,
     ) -> Option<Result<SatisfiedConstraint, Error>> {
-        if height >= *n {
+        if age >= *n {
             self.push(Element::Satisfied);
             Some(Ok(SatisfiedConstraint::RelativeTimelock { time: *n }))
         } else {