Seawater

* Coding changes to enable functions to return the same shape vector as the input arguments. In previous releases, some functions returned column vectors for row vector input. Also some other tidying up.

* New routine `satAr`. Solubility of Ar in seawater.
* New routine `satN2`. Solubility of N2 in seawater.
* New routine `satO2`. Solubility of O2 in seawater.
* Updated `test` to include tests for above.

Version 1.2e

* Fixed bug in `alpha` where temp used in calculations regardless of the keyword.

Version 1.2d

* `bfrq` now also returns potential vorticity. Thanks to Greg Johnson (gjohnsonpmel.noaa.gov).
* OMEGA=7.29e-5 was changed to OMEGA=7.292e-5 in `gvel` to be consistent with `f`.
* **Important API change**: The usage of `alpha`, `beta` and `aonb` routines has changed! All these routines expect (S,T,P) to be passed instead of (S,PTMP,P) as in previous releases of seawater. Fast execution can still be obtained by passing ptmp=True.

* Fixed a bug in `bfrq` where empty LAT was needed as argument when no latitude values are being passed.
* Now pass PRESSURE instead of DEPTH, more consistent though only a negligible change is answers.

* First official release and announcement on the networks.