Fixed bugs in RF measurement code and added white noise RF measurement

Fixed bug where the GUI couldn't access the appropriate coordinates
within the RF views, because it was using the wrong sheet2matrixidx
function. Also fixed bug where GUI tried to pass the measurement sheet
to the measurement function, which had no sheet parameter. Added the
ability to continue an RF measurement to the ReverseCorrelation
code. Added GUI entries for both positional and white noise RF
measurements.