Changeset 6950

This revision holds the developments made by Salma Tafasca during her PhD, while r6949 is equivalent to branch 2.2 r6594.
It allows ORCHIDEE to:
(1) read soil hydraulic parameters instead of soil texture maps or impose a uniform soil texture all over land, using keywords SPMIPEXP and EXP4;
(2) cancel the effect of roots on Ks with new keyword KFACT_ROOT_TYPE;
(3) introduce a 13th soil texture class for clay oxisols in addition to the 12 USDA classes
(with thermal parameters equal to the ones of clay).
These changes to branch 2.2 have been tested in Salma's PhD simulations, and are fully compatible with former ways to control soil texture and hydraulic parameters.