Unicode COMM tags are not written correctly

[Mbucari]

When writing a unicode COMM tag, the null tag description is missing the BOM prefix.

NAudio.Lame/LameDLLWrap/LibMp3Lame.cs

Line 614 in ed76eb6

return CheckResult(NativeMethods.id3tag_set_comment_utf16(context, "zxx", (byte[])null, data));

To correct this, do something like:

return CheckResult(NativeMethods.id3tag_set_comment_utf16(context, "zxx", UCS2.GetBytes(string.Empty), data));