Automatically adjust plot range for `checkFresnelNumbers`

Range of plotted frequency spectrum is automatically adjusted using the guessed Fresnel number.

For small Fresnel numbers (deeply holographic regime) only the first CTF minima are plotted.

This code change add the value maxNumPlottedCTFPeriods = "auto" which is now also used by default. If numeric values are passed (as used before) the automatic scaling is not used and thus the functions behavior is not altered.