Update to use v2-alpha branch

The V2-alpha branch supports small file optimizations which can help increase the utilization of flash when small files are prevalent. It also adds support for metadata, which means we can start adding things like file creation times, if desired (not yet).
esp8266 · d-a-v · May 25, 2019 · Dec 15, 2018 · Jan 7, 2019 · Jan 7, 2019
commit 13e985c0675328707f97d6f65b011736cc6f2d45
diff --git a/libraries/LittleFS/lib/littlefs b/libraries/LittleFS/lib/littlefs
diff --git a/libraries/LittleFS/src/LittleFS.h b/libraries/LittleFS/src/LittleFS.h
@@ -71,11 +71,15 @@ class LittleFSImpl : public FSImpl
         _lfs_cfg.prog_size = _pageSize;
         _lfs_cfg.block_size =  _blockSize;
         _lfs_cfg.block_count = _size / _blockSize;
-        _lfs_cfg.lookahead = 256;
+	_lfs_cfg.block_cycles = 16; // TODO - need better explanation
+	_lfs_cfg.cache_size = _blockSize;
+        _lfs_cfg.lookahead_size = 256;
         _lfs_cfg.read_buffer = nullptr;
         _lfs_cfg.prog_buffer = nullptr;
         _lfs_cfg.lookahead_buffer = nullptr;
-        _lfs_cfg.file_buffer = nullptr;
+        _lfs_cfg.name_max = 0;
+        _lfs_cfg.file_max = 0;
+        _lfs_cfg.attr_max = 0;
     }
 
     ~LittleFSImpl() {
@@ -234,19 +238,11 @@ class LittleFSImpl : public FSImpl
         return _mounted;
     }
 
-    static int _lfs_traverse_cb(void *p, lfs_block_t b) {
-        (void) b;
-        *(lfs_size_t *)p += 1;
-        return 0;
-    }
-
     int _getUsedBlocks() {
-        lfs_size_t in_use = 0;
         if (!_mounted) {
             return 0;
         }
-        int err = lfs_traverse(&_lfs, _lfs_traverse_cb, &in_use);
-        return err ? 0 : in_use;
+        return lfs_fs_size(&_lfs);
     }
 
     static int _getFlags(OpenMode openMode, AccessMode accessMode) {