Alt and Shift key binding support

[xxzozaxx]

hey, thanks for your great effort on this program, it's just amazing, and I'm looking forward to contribute with you awesome guys.

second, I just wonder if there is a default way to handle alt key binding, for example we have ^z to undo -which is Ctl+z- Could I make somthing like Alt+z.

Third thing is the current state Ctl+z is the same as Ctl+Shift+z (Ctl+Z). who could I bind to z and Z differently ?!

[fhs]

See #5.

I recall devdraw not sending some key modifier (at least on Linux). That might limit us on what we can bind to.

[xxzozaxx]

See #5.

Oh I see, there is WIP.