Update of Readme

I added explanations to the blocking nature of the setCompareChannels() function and introduced the function setCompareChannels_nonblock().

Furthermore I changed the code for the delays when changing channels from

        delayAccToRate(rate);
        delayAccToRate(rate);

to

        for(int i=0; i<2; i++){ 
            delayAccToRate(rate);
        }    

because some people considered this to be copy/paste error.