Allow wav, flac, msgpack type optional files

[stbinan]

.msgpack for media files, including the media files that have been uploaded, will be generated when user submits a new file.

[Emeraude]

I haven't looked at the Bigfile plugin, but I suppose enabling them require more code than allowing the .msgpack files. Am I right?

[stbinan]

@Emeraude I haven't looked into the Bigfile plugin, but I think it's not necessary. Before there was a new website with only plain Html and links to optional files and it still worked very well when downloading large files.
In contrast, although I've generated .msgpack for my files in IFS, but after I downloaded a file from from another client, the file didn't show up in the file manager. It's probably a bug from IFS itself.

[Emeraude]

I'll take a look at the plugin before accepting your PR.
I'm a bit busy, it may take some time.