AltGr flips shader modes on Windows

[giraluna]

The editor uses Ctrl+Alt as a hotkey for switching between shader modes:

Shdr/sources/shdr/App.coffee

Line 294 in 8ff3c9f

else if e.ctrlKey and e.altKey # Flip Shader

Windows maps AltGr to Ctrl+Alt. AltGr is required to type special characters like braces on several keyboard layouts. See Why Ctrl+Alt shouldn’t be used as a shortcut modifier.