Fix dateline wraparound effects for domain plotting.
Added test for the dateline wraparound plotting issue.
Raise NotImplementedError for non-rectangular domains and raydensity
plotting.
Raydensity plots now work in the non-rotated domain.

This has the advantage to also work for domains including the poles
or strangely distorted ones. The actual plots are calculated in the
non-rotated domain and they are then rotated to the final domain.