Silence mac warnings

Along with the audio2 merge, we enabled unused and conversion warnings on Mac, so that warnings were closer to uniform across all supported platforms.  This exposed some 156 warnings, this PR reduces it down to 56 with Xcode 5.1.1.

I left the files alone that need closer attention - some appear that a decision needs to be made whether they will support large ints or not, such as ObjLoader, Buffer.  I've talked with Andrew and he has plans for dealing with Stream for 64-bit support separately.

There are still warnings from boost headers.  I disabled warnings in the xcode project settings for other third-party .cpp's, but that doesn't work for headers.

Also cleaned up some minor bracket formatting in Stream.h and Timeline.h, which will hopefully contribute towards making it clearer to other people submitting PR's what the correct format should be.

Open to suggestions about what to do with this, though I think it would be nice to get the warning count as close to zero as easily possible, so as to allow warnings from new code to be more transparent.