`rescaledata` rework

[stestoll]

• Remove modes lsq0, lsq1, lsq2 , since they perform baseline correction, which should be done with by basecorr.
• Remove minmax mode. It also adds a shift, corresponding to baseline correction.
• rescaledata(y,yref) should do lsq rescaling.
• rescaledata(y) should do maxabs rescaling.
• Extend to work for 2D data (along columns, along rows, for the entire 2D dataset).
• Introduce area normalization: area for single integral, area2 for double integral (CW EPR). Example: rescaledata(y,'area2')