Fix a memory leak

`drop` does not remove an element in-place.
To learn what it does, I'll refer you to the scala collection docs.

src/main/scala/ocelot/desktop/windows/ComputerWindow.scala

@@ -51,10 +51,11 @@ class ComputerWindow(computerAware: ComputerAware) extends BasicWindow {
             private var lastTick = OcelotDesktop.ticker.tick
 
             def appendHistoryValue(value: Float): Unit = {
-              history.append(value)
+              if (history.length > historySize) {
+                history.remove(0)
+              }
 
-              if (history.length > historySize)
-                history.drop(0)
+              history.append(value)
             }
 
             def tickUpdate(): Unit = {}