First draft of storage APIs (#122)

* First draft of storage APIs

* bumped pxt-core

* using fixed instances to seprate temp from permanent

* send console to storage

* sim support

* missing sim stubs

* adding storage blocks

* more sim support

* remove storage from default package

* fix rendering of ms

* render raw ms

* slize at better place

* duplicate bundled dir

* refactor limit

* simplify limit logic

sim/state/storage.ts

@@ -0,0 +1,23 @@
+namespace pxsim.storage {
+    export function __stringToBuffer(s: string): RefBuffer {
+        // TODO
+        return new RefBuffer(new Uint8Array([]));
+    }
+
+    export function __bufferToString(b: RefBuffer): string {
+        // TODO
+        return "";
+    }
+
+    export function __mkdir(fn: string) {
+        // TODO
+    }
+
+    export function __unlink(filename: string): void { 
+        // TODO
+    }
+
+    export function __truncate(filename: string): void { 
+        // TODO
+    }
+}