Resize and keep aspect ratio

Resize and keep aspect ratio

New options to manage how the new feature is handled:
keepAspectRatio: "true" = add black bands razer than deforming picture. Default is "false".
cursorInBlackBandsInFullscreen: used only in fullscreen mode. "false" = the cursor position will be "streched" making impossible to go in the black bands. "true" = cursor can go in black bands but will be invisible. Default is "false".
cursorInBlackBandsInWindow: same as cursorInBlackBandsInFullscreen but is used only in window with borders. Default is "true" to avoid cursor jumps when going into or out of the game window.
cursorInBlackBandsInBorderlessWindow: same as cursorInBlackBandsInFullscreen but is used only in borderless window. Default is "false" because main interest of borderless window is fullscreen for dual screen users.

When OpenGL is deactivated the way the resizing is done is not optimal, using a supplementary buffer. User deactivating OpenGL should deactivate this feature for the moment.