integrate BacklashCompensation

[zarfld]

on pokeyslib following functions are available
POKEYSDECL int32_t PK_PEv2_BacklashCompensationSettings_Get(sPoKeysDevice * device);
POKEYSDECL int32_t PK_PEv2_BacklashCompensationSettings_Set(sPoKeysDevice * device);

sPoKeysPEv2 provides:
uint16_t BacklashWidth[8]; // half of real backlash width
int16_t BacklashRegister[8]; // current value of the backlash register
uint8_t BacklashAcceleration[8]; // in pulses per ms^2
uint8_t BacklashCompensationEnabled;