Fix typo in onPulse; hook up createBuffer

libs/microbit/buffer.cpp

@@ -1,5 +1,6 @@
 #include "ksbit.h"
 
+// keep in sync with github/pxt/pxtsim/libgeneric.ts
 enum class NumberFormat {
     Int8LE = 1,
     UInt8LE,

sim/libmbit.ts

@@ -514,13 +514,17 @@ namespace pxsim.radio {
 }
 
 namespace pxsim.pins {
-    export function onPulse(name: number, pulse: number, body: RefAction) {
+    export function onPulsed(name: number, pulse: number, body: RefAction) {
     }
 
     export function pulseDuration(): number {
         return 0;
     }
 
+    export function createBuffer(sz:number) {
+        return pxsim.BufferMethods.createBuffer(sz)
+    }
+
     export function digitalReadPin(pinId: number): number {
         let pin = getPin(pinId);
         if (!pin) return;