Increasing Resolution

This is a basic patch for increasing viewport resolution on Grim Fandango (opengl), via ResidualVM's preferences/ini file. The preference keys are gameWidth and gameHeight like...

gameWidth=1280
gameHeight=960

If they are not found, it creates the viewport at normal 640x480 resolution.

I changed the filtering to linear except for backgrounds (createbitmap) where some rooms had artifacts :?

The rest of the changes are for taking into account the actual scaling when doing projections and raycasts. This way the point&click still runs. I couldn't find where the mouse position is initialized to center it, as it starts at a offscreen position.