Create rotation module

[celineaubert]

In a rotation crops are cultivated one after the other. Therefore the experimental conditions will be different for each crop. When rotation is selected, add as many experimental conditions for the rotationas there are crops chosen. For example, if there are 3 crops in a rotation, we need to have 3 experiment conditions modules.

For rotation experiments across seasons, we also want to be able to assign treatments to plots manually - without automated randomization from AgroFIMS. e.g. Plots A and B have wheat in season 1 and plots C and D have potato - but in season 2, plots A and B will have potato and C and D must have wheat. Randomized assignment of treatments across the FBs for these 2 seasons is incorrect.