#24 Fix shift sounds

Hi,

This patch fix a small issue in the shift sounds. The function getShiftDirection returns targetgear_rel, but this variable doesn't always contain the last shift direction leading to incorrect sounds at upshift/downshift.

[Emanuele Sorce]

Thanks Kirada. I will review then merge your patch soon :D

[Emanuele Sorce]

Thanks for the patience. I merged your fix in [r964]. Thanks for the contribution!