add an “Sort by x values” checkbox to enable profile data point sorting before plotting

[Andreas Janz]

Originally requested by @Agustin Lobo in #891.

Hyperspectral sensors with seperate VNIR and SWIR detectors (e.g. PRISMA and EnMAP) do have a spectral overlap. When simply plotting such data, you get a “loop” in the profile, when plotted agains the wavelength.

It is proposed to add a “Sort by x values” checkbox, to allow for plotting sorted profiles instead.

[Benjamin Jakimow]

resolves #906

→ <<cset 362bb477bb07>>