[src] new options for Courlis (grain size evol & variable morpho width
New options for Courlis bedload :
- grain size evolution variable along the reach (direct modification of the grain for each profile with no physical model processes for the evolution)
- morphological width variable along the reach : available only with lefort 2014 formula which integrates this variable
Those two options are mixed in this MR because they are base on the reading of one file where are indicating values for each profiles of grain size and variable width.