plot_tools - added darken, alters colors darker, and label_subplot_spec, adds text to a subplot_spec like a label
run_tools  - added call tracing
vecgeom    - added fast unitvec_f2d for 2d data, works on last dim
split_lambert_transform - updated to meet matplotlib >=1.2 requirements- _non_affine added to transform calls
added a very simple test for unitvec, unitvec_f2d