Add numpad support

[samiksome92]

This adds basic numpad support. The numpad keys are mapped in a vertically inverted manner (1,2,3->7,8,9) and (7,8,9->1,2,3) as layout is vertically inverted in mobile phone keypads.

[recompileorg]

You should change lines like this:
case KeyEvent.VK_0: case KeyEvent.VK_NUMPAD0: return Mobile.KEY_NUM0;
to:
case KeyEvent.VK_NUMPAD0: return Mobile.KEY_NUM0;

[samiksome92]

So no fall throughs, but a separate set of case statements entirely right? Done

[recompileorg]

Yes. If you'll look just a few lines above, you'll see that those cases are already handled.

You should also consider that users who don't have or aren't using a numpad (most laptop users) will be very confused when they press 1 and get a 7 instead. As we have separate constants for the numpad numbers, it only makes sense to use those for the inverted numpad. You can see this in the SDL version, as Hex pointed out.

[recompileorg]

Looks good

[samiksome92]

I don't understand. the VK_NUMPAD signals are only generated if someone presses a the numpad keys right? In that case people who don't have numpad would still not have any problems. Someone pressing non-numpad 7 would still get 7 since the VK_7 matches and returns Mobile.KEY_NUM7

[samiksome92]

Thanks for the merge