Work still to do for spatialmath-python

classes

Empty constructor for all
== != for all classes
UnitQuaternion
- angle
- vectorization of vec3 multiplication, v3mul
norm, print, plot for all classes
use @ operator for composition with normalization
vectorization of RPY, Eul, AngVec constructors and converters
add from/to to transformations, add check that multiplication is valid
- keep class variables for a dict of all poses
- use dot to make a graph
- use Unicode sub/superscripts to format this nicely (not all letters possible)
UnitQuaternion interp, vectorize
plot/animate for UnitQuaternion

add support channels to doco
cleanup all file headers
- just the purpose
- acknowledgement/history to comments
remove assertions, replace with ValueError
autopep8
linting
revise all error messages, more consistent

Travis matrix test for different Python/numpy versions
fixup consequences of spatialmath-matlab name change
- petercorke.com download page
- Travis build for RTB matlab
- MathWorks file exchange
- badges in README