API changes:
Bctides: variables `iettype, ifltype, isatype, itetype` are deprecated.
New variables were added:
- flags: requried, bctypes for each boundary [[iettype, ifltype, itetype, isatype], [...], [...], ...]
- add_earth_tidal: optional, default is True
- ethconst: optional, needed when using constant elevation along the boundary (iettype=2), which is given as [v1, v2, v3, ...]
- vthconst: optional, needed when using constant discharge (ifltype=2)
- tthconst: optional, needed when using constant temperatur (itetype=2)
- sthconst: optional, needed when using constant temperature (isatype=2)
- tobc: optional, nudging factor, needed when itetype is not 0, [v1, v2, v3, ...]
- sobc: optional, nudging factor for salinity, needed when isatype is not 0, [v1, v2, v3, ...]
- relax: optional, needed when ifttype=-4, [rel1, rel2]