trimming routine and slamax

[rgknox]

It looks like trimming does not use slamax to inform on the actual SLA of the leaf layers during trimming. It is used as a cap of some type, but that is it.

https://github.com/NGEET/fates/blob/master/biogeochem/EDPhysiologyMod.F90#L525-L529

[rgknox]

sla_max never informed the curvature of the sla function with depth, no issue, closing