output: add functions for custom motor speed ramping

[JakubVanek]

Hi everyone,

this PR exposes the EV3 motor ramping functionality.

Best regards,

Jakub

[JakubVanek]

I have tested this patch and it works correctly.
Test program:

#include "ev3.h"
#include "ev3_command.h"

int main() {

    RotateMotorRamp(OUT_AD, 100, 180, 360, 180, true);
    RotateMotorRampNoWait(OUT_A, -50, 10, 180, 10, true);
    RotateMotorRampNoWait(OUT_D, +50, 10, 180, 10, true);
    Wait(1000);

    return 0;
}

Video of the motors: https://photos.app.goo.gl/hCEJkwBtkHZgr4fY9