Parameter bounds structures for LBSGSB

[leobpujol]

Current bounds are hardcoded.

• Need to create a bound structure for each new and old parameter
• Need to make it accessible via Python
• Need to add default bound values

NB: during the assimilation, process, all bounds are all added to the existing control_ubound/control_lbound structures, in a specific order. To keep things clear for the user, I think the addition of these intermediate bounds structures is pertinent.