add ignore shim

Author: thomasjball

libs/core/codal.cpp

@@ -102,6 +102,12 @@ void registerWithDal(int id, int event, Action a, int flags) {
     registerGCPtr(a);
 }
 
+void unregisterFromDal(int id, int event, Action a) {
+    uBit.messageBus.ignore(id, event, dispatchForeground, a);
+    decr(a);
+    unregisterGCPtr(a);
+}
+
 void fiberDone(void *a) {
     decr((Action)a);
     unregisterGCPtr((Action)a);

libs/core/control.cpp

@@ -312,6 +312,14 @@ namespace control {
         registerWithDal(src, value, handler, (int)flags);
     }
 
+    /**
+     * Unregisters an event handler.
+     */
+    //%
+    void ignoreEvent(int src, int value, Action handler) {
+        unregisterFromDal(src, value, handler);
+    }
+
     /**
     * Gets the value of the last event executed on the bus
     */