Add tangent output to torus knot node and optimize its code

- add tangent calculation and output to the node
No need to restrict the node's phase parameters to only positive values.. the spin/revolution phase can go in both directions.
- minor optimization
- conditionally calculate normals and tangents based on node extra parameters (on by default)
- remove the min bounds from the phase parameters
- update comments and documenation
- cleanup unused code
- PEPify the code

docs/nodes/generator/torusKnot.rst

@@ -75,14 +75,19 @@ A set of extra parameters are available on the property panel. These parameters
 +-------------------------+------------+------------+-----------------------------------------------+
 | **Scale**               |  Float     |  1.00      |  Scales both radii by this amount             |
 +-------------------------+------------+------------+-----------------------------------------------+
+| **Normalize Tangents**  |  Bool      |  True      |  Normalize the TANGENT vectors [2]            |
++-------------------------+------------+------------+-----------------------------------------------+
+| **Normalize Normals**   |  Bool      |  True      |  Normalize the NORMAL vectors [2]             |
++-------------------------+------------+------------+-----------------------------------------------+
 
 Notes:
 [1] Used without adaptive resolution these allow to create aliased torus knots resulting in all sorts of interesting shaped knots.
+[2] Turn off normalization to save computation whenever the output vectors do not need to be normalized.
 
 Outputs
 -------
 
-**Vertices**, **Edges** and **Normals**
+**Vertices**, **Edges**, **Tangents** and **Normals**
 All outputs will be generated when connected.