cbar is the cf-plot interface to the Matplotlib colorbar routine
labels - colorbar labels
orientation - orientation 'horizontal' or 'vertical'
position - user specified colorbar position in normalised
plot coordinates [left, bottom, width, height]
shrink - default=1.0 - scale colorbar along length
fraction - default = 0.21 - space for the colorbar in
normalised plot coordinates
title - title for the colorbar
fontsize - font size for the colorbar text
fontweight - font weight for the colorbar text
text_up_down - label division text up and down starting with up
text_down_up - label division text down and up starting with down
drawedges - Draw internal delimeter lines in colorbar
levs - colorbar levels
thick - set height of colorbar - default = 0.015,
in normalised plot coordinates
anchor - default=0.3 - anchor point of colorbar within the fraction space.
0.0 = close to plot, 1.0 = further away
extend = None - extensions for colorbar. The default is for extensions at
mid = False - label mid points of colours rather than the boundaries
verbose = None