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

libs/storage/storage.cpp

@@ -0,0 +1,44 @@
+#include "pxt.h"
+
+#include <sys/types.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+namespace storage {
+
+/** Will be moved. */
+//%
+Buffer __stringToBuffer(String s) {
+    return mkBuffer((uint8_t *)s->data, s->length);
+}
+
+/** Will be moved. */
+//%
+String __bufferToString(Buffer s) {
+    return mkString((char*)s->data, s->length);
+}
+
+//%
+void __init() {
+    // do nothing
+}
+
+//%
+void __unlink(String filename) {
+    ::unlink(filename->data);
+}
+
+//%
+void __truncate(String filename) {
+    int fd = open(filename->data, O_CREAT | O_TRUNC | O_WRONLY, 0777);
+    close(fd);
+}
+
+/** Create named directory. */
+//%
+void __mkdir(String filename) {
+    ::mkdir(filename->data, 0777);
+}
+
+} // namespace storage