[PCS] set the shape function order from config assuming all the primary variables use the same order

[Test] Added two large size tests for liquid flow process

Liquid flow process

Where g is the gravitational acceleration.

With this improvement, the if-condition for isotropic anisotropic
is moved outside the integration loop.

and gravitational_term

one variable name, and made some other minor improvements
according to the comments by Dima and Tom.

rebased the data repository.

and made some other minor changes.

and for axisymmetical problems.