Add small keyboard tester module
Add different keyboard emulation modes

Virtual: As before (key press events get translated to the corresponding
US keyboard keys)

ParaVirtual: Like Virtual, but only character codes are provided, no scan
codes (like the JS emulator)

NoParaVirtual: Like Virtual, but only scancodes are provided.

Native: Map each keyboard key 1:1 to PS2 scancode (like @pdewacht's
emulator is doing it)

Hybrid: Map non-letter keys like Native, and letter keys like Virtual.
Also keep track of the Shift state and toggle it before typing a letter
key (and back after releasing it or before pressing a native key).