Rescale y-axis to 0,1
This rescaling works differently to x rescaling because y and y end need to be rescaled together
     
    
    Usage
    rescale01y(y, yend, ylim = NULL)
 
    
    Arguments
- y, yend
- The input arrays to be rescaled 
- ylim
- The limit of the rescaling. If NULL, the maximum value from y and yend is used. 
 
    
    Value
    A list of two rescaled arrays based on the input array and provided limit that provides values between 0 and 1