Fixed XRandR code to change resolution on the correct monitor in a multi-monitor setup.

Fixed copying headers to the Framework

Fixed bug where SDL thought the window was shown and it wasn't actually.

From Rick Johnson:

Here's the call pattern:

Create the window hidden
The game tells it to adjust the window position
Make the window visible.

A problem arises from the SetWindowsPos() - the default behavior of that would cause a WM_ACTIVATE message to be passed, of which SDL interprets that as the window now becoming visible and sets the flags. The window is not visible though. Now, when you try to call ShowWindow() - SDL sees those flags as indicating that the window is visible and early returns.

My proposed fix was that if we are calling set windows position and we aren't visible, add on the flag SWP_NOACTIVATE, which tells windows to not send down the WM_ACTIVATE flag.

Updated iOS Readme to reflect Game Center integration changes.

Fixed texture list when swapping textures (thanks Drake Wilson!)

Initialized default scale for software renderer (thanks Marcus von Appen!)

Fixed a compiler warning

Added SDL_RenderSetLogicalSize() and SDL_RenderGetLogicalSize()

The viewport is already scaled to the output coordinates

Added SDL_RenderSetScale() and SDL_RenderGetScale()