* New features:
* For some methods in RegularSurface(), a ``sampling`` key is added which in
addition to default `bilinear` interpolation also can use `nearest node` sampling.
The latter can be useful e.g. for discrete maps such as facies. Closes 462.
* For Wells(), add a method ``create_surf_distance_log`` that makes a well log
that is distance to a surface, 461.
* For Wells(), add a method that can remove (mask) data based on discrete logs, i.e.
remove shoulder-bed effects, 457.
* A pre-release (i.e. experimental!) support for free-form metadata and new formats:
* A separate MetaData class for each major data-type.
* Native XTGeo formats. Should be very fast and support metadata.
* Support for HDF-5 formats, should be quite/very fast, support metadata and
compression.
* In relation to this, more automatic format detection is initiated. This means
in practice that the key ``fformat`` and/or file extension rules will not be
needed in many cases, as xtgeo will detect the file format by inspection the file
itself. This is in particular useful for binary memory streams.
* As a side note, the HDF support change the external requirements for xtgeo as e.g.
the `h5py` package and more are now needed.
* Improvements and bug fixes:
* Improvements on missing or wrong ``values`` key when dealing with RegularSurface(),
relates to bug report 450.
* When reading a discrete 3D property from Roxar API the codes may in
some cases return an empty dictionary. This is now fixed, 465.
* Fix use realisations from Roxar API (3D grids), 443.
* General improvements in documentation, e.g. clearer guidelines for contributions.