Improve multiple spectra values

[lpatiny]

We should add the possibility to click twice on a cell and be able to add a new value.

We could also add a possibility to set the max value globally. Having in the preference of the module the max value would make sense as well.

To be discussed with Regis project.

Currently we have 4 different algorithms:

• relative integral
• absolute integral
• max intensity in the specified range
• min intensity in the specified range