OS X Bundle: Allow more than one instance of the player.

[franzf]

If you already have a file open on mpv.app, double clicking on another file to open it gives you this message:

mpv 46f8429, compiled with Homebrew, OS X 10.8.2

[pigoz]

With Cocoa you can't allow more than one instance of the player by simply spawning another process. Unfortunately the correct way would be implementing a "Document based" Cocoa application which I'm not sure how should interact with the playlist and wouldn't interact very well with the rest of mpv.

I think if you open a new file from the finder the player should use that file to replace the current playlist. That, at least, should be easier to implement.

[pigoz]

The above commit doesn't allow more than one instance of the player, but allows to open new files in the current running instance.

[tewe]

This throws away your playback position. A confirmation dialog would help.

[pigoz]

mpv doesn't remember the playback position for any file, why it should in this case?

[tewe]

No Mac app should lose state when Finder asks it to open a file. Either save the position or ask for confirmation before opening the new file, otherwise you break user expectations, which leads to frustration.