g13 - Go library for Logitech G13

Note	This is work in progress.

USB protocol

8 bytes:

1    allways 1?
2-3  stick x, y (0-255)
4-8  keys:
4: G1  G2  G3  G4  G5  G6  G7  G8
5: G9  G10 G11 G12 G13 G14 G15 G16
6: G17 G18 G19 G20 G21 G22 undef1 light_state
7: BD  L1  L2  L3  L4  M1  M2  M3
8: MR left right stick undef2 light1 light2 toggle