Step over bug

[theodore-norvell]

When stepping over a call to a closure, the interpretation should stop as soon as the closure has returned.

For example, if state is

 call( var[*]  var[n]->5 call( var[factorial]->closure call( var[-] var[n] num[1] )->4 ) )

and the call to factorial is selected, then the next state should show the state before the multiplication.

 call( var[*]  var[n]->5 call( var[factorial]->closure call( var[-] var[n] num[1] ) )->24 )

Currently, it shows the state after the multiplication.

 call( var[*]  var[n] call( var[factorial]->closure call( var[-] var[n] num[1] ) ) )->120

[theodore-norvell]

Fixed.