[IMP] stock: modify move initial demand should not always unsreserve
[IMP] stock: modify move initial demand should not always unsreserve

Write method on stock move always unreserve concerning move if
initial demand is modified. Unreserve will delete all move lines
linked to the move including those already modified.

Thus modify initial demand(unreserve) will destroy all the
job done by the user.

This commit will only unreserve move is the initial demand
is smaller than the quantity reserved (could be improved by dropping
only few move lines). If the initial demand is greater than the
reserved quantity it will not unreserve but only change the
state to partially avaialbe.

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo