Adapt GW code to use the same soil properties as the main branch.

[ccarouge]

In the GW work, two soil properties have incompatible changes with the main part of the code:

• soil%hyds_vec is in mm/s while soil%hyds is in m/s.
• soil%sucs_vec is of the opposite sign compared to soil%sucs.

This means the ranges for each parameter and variable defined in ranges_type will not be compatible with the GW parameters. It also introduces sign changes and unit conversions at various places in the initialisation routines.

The preferred solution is to change the GW code to use the same units and sign convention as the main code. This should also be accompanied with a corresponding change in the GW input files.