Plotting: add easy selection of region to plot (i.e. Lofoten, west-coast, ..)

[inakbk]

File utils.py, inside function subset_variable() some lon and lat values are already set as default.

Add feature to select from a list of strings (names) different regions of Norway to plot, some smaller and some larger regions, and one for all points.
Consider adding this in a separate dictionary stored in a separate file.