rt: Allow deleting symbols at runtime. This is NEVER exposed to the language

Author: hexaredecimal

src/main/java/org/piccode/rt/Context.java

@@ -194,6 +194,12 @@ public void putLocal(String name, PiccodeValue value) {
 		frame.putLocal(name, value);
 	}
 
+	public void deleteLocal(String name) {
+		var frame = call_frames.peek();
+		frame.deleteLocal(name);
+	}
+
+
 	public PiccodeValue getValue(String name) {
 		if (call_frames.isEmpty()) {
 			return global_scope.get(name);

src/main/java/org/piccode/rt/StackFrame.java

@@ -78,4 +78,9 @@ public void dropScope() {
 		}
 	}
 
+	void deleteLocal(String name) {
+		var frame = scope_stack.peek();
+		frame.remove(name);
+	}
+
 }