Re-add not instruction I accidentally deleted

src/main.cpp

@@ -1895,6 +1895,38 @@ Literal exec(vector<Instruction> in, bool executingFunction) {
                     setVal(varRef.varName, final);
                 }
                 break;
+
+            /*
+                not instruction
+                Negates a boolean
+            */
+            case Instructions::Not:
+                if (l.args.size() < 2) {
+                    error("Could not find all arguments required for Not inbuilt");
+                }
+                {
+                    Literal boolean;
+                    Direct varRef;
+
+                    if (holds_alternative<Literal>(l.args[0])) {
+                        if (holds_alternative<bool>(get<Literal>(l.args[0]).val)) {
+                            boolean.val = !get<bool>(get<Literal>(l.args[0]).val);
+                        } else {
+                            error("First argument of not must be a boolean literal");
+                        }
+                    } else {
+                        error("First argument of not must be a boolean literal");
+                    }
+
+                    if (holds_alternative<Direct>(l.args[1])) {
+                        varRef = get<Direct>(l.args[1]);
+                    } else {
+                        error("Second argument of not must be a direct reference");
+                    }
+
+                    setVal(varRef.varName, boolean);
+                }
+                break;
             /*
                 jump instruction
                 Jumps to the line reference provided.