Standardize MIDI note numbers for drums

[vigliensoni]

The MIDI note numbers for the drums is currently inverted:

0, bass_drum 51;
1, snare_drum 49;
2, closed_hihat 50;
3, open_hihat 48;
4, low_tom 45;
5, mid_tom 46;
6, high_tom 42;
7, hand_clap 38;
8, rim_shot 36;

It should be exactly the opposite.

The bad thing is that the already created models will be using this mapping.