Added support log-norm on demand, steps in color bar and for gray center of color
bar (for diff plots)
Added support for manually setting the positions of the colorbar ticks.
bugfix: vars_tempice had only one element and ended up as string
instead of list.

added a ','
Added support for overlaying a second variable as contour lines.

--overlay and --overlay_file (optional) specify what to plot from where
Support for masking the plot variable using another variable

--mask_file
--mask_var
--mask_threshold (to be exceeded)
--mask_abs (take absolute value for threshold comparison)
support for getting coordinates from external coord-file --coords

helps for plotting extra-files
made two sys.exit() return 1 instead of 0
introduce scaling factor for data. not well tested yet
Custom set levels for stepwise colorbar --levels=-10,-4,8,36 or so...
give --level -l as shortcut
make ncol/nrow computation work for 1 column only (or so)
Add Alaska Albers projection (might blow things up, but should not act
if not called...)
JIF Specific lon/lat spacings
various colormap setting / ... changes and two colormap additions
updated units for SMB changes to mm w.e. yr-1
check for existence of colorbar_label before adding it -- not
necessarily good idea to do.
Added support for country borders in plots