EMI DEMO: ALT+Enter to toggle fullscreen causes broken textures

[sev-]

Using alt+enter to go from windowed to fullscreen or fullscreen to windowed cause a change in texture behavior. Shown here:

(Note: This is shown using the pending lighting fixes, but the same texture issues happen in current master.)

Guybrush seems to be textured using the current set's background image, but all other models seem to loose their textures and only be solid colored.

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This is using OpenGL. Doing alt+enter using software succeeds in creating a save file but crashes after savegameRestore finishes.

​https://github.com/residualvm/residualvm/issues/929

[mparnaudeau]

Now that EMI management is in ScummVM, I see no effect of ALT+Enter to switch between window and fullscreen modes.