Fixes issue #146

[albertosottile]

On macOS, fixes the "Add to the bottom of shared playlist" QFIleDialog with the QtGui.QFileDialog.DontUseNativeDialog workaround used before. Also fixes drag and drop of media files on both the "List of who is playing what" and "Shared playlist" boxes.

Drawbacks: requires PyObjC. If merged, the installation instructions should be updated to include pip install pyobjc.

[Et0h]

http://www.birving.com/blog/2015/09/29/drag-and-drop-files-into-gui-using/ indicates one should install pyobjc-core before installing which may relate to the issue at https://stackoverflow.com/questions/36813269/issue-with-installing-pyobjc-for-python but I'm not sure. As far as I can tell, if we're using PySide 1 we need to use NSURL to support file dragging and that means we need PyObjC. Are there any major drawbacks to requiring it other than requirement bloat?

[albertosottile]

That birving.com page is what I used as reference to write this workaround. You are right, we need NSURL and I did not find an alternative that does not rely on PyObjC. I do not see any particular problem in requiring it in the instructions, my concern was about the size of PyObjC. Including it in a .app bundle will increase the size of the packaged file.

[albertosottile]

Just an FYI, the current master of Syncplay, when packaged in an .app, is about 39.9 MB. The inclusion of the Foundation module from pyobjc increased it to about 41.4 MB. So I guess that was too much ado about nothing.

Also, to further complicate things: [EDITED] it appears that the drag and drop problem arises only from a certain version of macOS (I guess 10.9 but I might be wrong) and affects all the subsequent releases. At least on these versions, It does not matter if the software is executed from the python script or packed in a .app.