bug in nfd_cocoa.m (some calls don't restore focus to main window)

[andykt]

Much thanks for your work Alloyed! Just wanted to report a bug in nfd_cocoa.m.
The NFD_OpenDialogMultiple and NFD_SaveDialog routines are not resetting the focus to the main window when they finish. NFD_OpenDialog has no such problem because it uses these two calls:

NSWindow *keyWindow = [[NSApplication sharedApplication] keyWindow];
...
[keyWindow makeKeyAndOrderFront:nil];

To fix the bug just add these calls to the same places in NFD_OpenDialogMultiple and NFD_SaveDialog.