Initial sim implementation

sim/state/util.ts

@@ -0,0 +1,7 @@
+namespace pxsim.util {
+
+    export function map16Bit(buffer: Uint8Array, index: number, value: number) {
+        buffer[index] = (value >> 8) & 0xff;
+        buffer[index+1] = value & 0xff;
+    }
+}