This 'fixes' T68554: 'API mathutils.geometry.tessellate_polygon returns
bad results sometimes' by documenting the limitations of the current
implementation.
I've also added a unit test for the function, so that any change in this
behaviour will get noticed.
No functional changes.
Added conversion to and from exponential map representation. This
representation is useful for interpolation of > 2 quaternions, or in
PD controllers.
Implementation in C functions quat_to_expmap,
quat_normalized_to_expmap, and expmap_to_quat with Python API, unit
tests and documentation.
Added Quaternion.to_exponential_map() and Quaternion(3-vector) to
Python API.
Reviewers: campbellbarton
Projects: #bf_blender
Differential Revision: https://developer.blender.org/D1049
Those two mimic our BLI invert_m4_m4_safe - they add a small offset to diagonal values,
in case org matrix is degenerated, and if still non-invertible, return identity matrix.
Org patch by me, final enhanced version by ideasman42, many thanks!
