Integration of ihcantabria wave models

Integration of functionality produced by The Environmental Hydraulics Institute "IHCantabria" (http://www.ihcantabria.com/en/)

- Original code introduced in commit 95e9467e
- Restructured and updated by OpenCFD into a new `waveModels` library available to the interFoam family of solvers

Main source:
`$FOAM_SRC/waveModels`

Tutorials:
`$FOAM_TUTORIALS/multiphase/interFoam/waveExample*`

Capabilities include:
- Wave generation
- Solitary wave using Boussinesq theory
- Cnoidal wave theory
- StokesI, StokesII, StokesV wave theory
    
- Active wave absorption at the inflow/outflow boundaries based on shallow water theory

IHCantabria Authors:
- Javier Lopez Lara (jav.lopez@unican.es)
- Gabriel Barajas (barajasg@unican.es)
- Inigo Losada (losadai@unican.es)

See merge request !88