[Oberon] Large displays in Emulated RISC Oberon

[Charles Perkins]

I wished to be able to use the full resolution of my laptop (1440x900) from within the emulated Oberon system, so I have created patches for Peter de Wachter's oberon-risc-emu program which will (after patches are applied) create a new frame buffer in higher memory. 

Smaller screens still work the way they did before and I think that Oberon looks awesome at full screen and high resolution on my MacBook Air!

I have also modified Display.Mod and made a one-line change to Input.Mod to allow Oberon to use that new frame buffer when resolutions are greater than 1024 horizontal or 768 vertical. 

I have tested resolutions as high as 1920x1080 on an external monitor, it should work all the way up to 2048x2048. I have not tested on platforms other than the Mac.

The changes can be found at: https://github.com/charlesap/io

Chuck