新增：封面嵌入、歌词下载；修复Bug

src/main/utils/musicMeta.js

@@ -0,0 +1,14 @@
+const path = require('path')
+const mp3Meta = require('./mp3Meta')
+const flacMeta = require('./flacMeta')
+
+exports.setMeta = (filePath, meta) => {
+  switch (path.extname(filePath)) {
+    case '.mp3':
+      mp3Meta(filePath, meta)
+      break
+    case '.flac':
+      flacMeta(filePath, meta)
+      break
+  }
+}