tutorial on lookupTwist function

[rosebudflyaway]

This is related to issue 43, confirmed from math logic side, the lookupTwist function is correct when calling lookupTransform here.

Connects to #43

[wjwwood]

+1

[rosebudflyaway]

I found the notes on API review of lookupTwist. Questions are below:

transformTwist is commented out, is this function deprecated for tf2?

The member function lookupVelocity of class TransformListener is deprecated?

I suppose this would be replaced by lookupTwist of class Transformer ?

The lookupVelocity function call here are commented and seems to be replaced by the next 3 lines of code?

I guess this test file for transform_twist_test was written some time ago before some functions change API? Is there any suggestion on rewrite a test file or stick with this one (based on the portion of API changes)?

So much fun working on math, I will continue working on this to add a test case and make sure those frame transformation are correct!