Reduce warnings on OSX (July 2014 edition)

This is another Xcode warnings fix PR :)

The warnings in question are the 2 "Apple Mach-O Librarian" warnings, the repeated `gluBuild2DMipmaps` warnings and an Objective-C related warning that pops up in Xcode 6.

* GLUT and FMOD removed from "Other Linker Flags". As far as I can tell, these were always just being ignored anyway, until Xcode 5 actually made them into warnings. [More on that](http://stackoverflow.com/questions/22572610/how-to-fix-is-a-dynamic-library-not-added-to-the-static-library-warning)
* There was an NSURL being treated as an NSString in the QTKit renderer, it's fixed now and there shouldn't be any runtime difference at all due to the way Objective-C deals with types
* Did the same `#pragma` trick (#2966) in ofTexture to cut down on the warning barrage RE: `gluBuild2DMipmaps`. To be honest, I have no idea about how to actually fix that one, and the legacy / compatibility issues that'd go along with it :)

There's one more warning RE: NSAlert, that's fixed in #3058