Conversion from arbitrary Euler angles to quaternion

[AlexanderFabisch]

Features

• Add rotations.quaternion_from_angle
• Add quaternion_from_euler to convert from arbitrary Euler angles to quaternion
• Add matrix_from_euler to convert from arbitrary Euler angles to active rotation matrix
• Add euler_from_matrix to convert from active rotation matrix to arbitrary Euler angles

Deprecated

• rotations.quaternion_from_extrinsic_euler_xyz

[codecov-commenter]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage :thumbsup:

Coverage data is based on head (8e41125) compared to base (cc376d4). Patch coverage: 100.00% of modified lines in pull request are covered.

:exclamation: Current head 8e41125 differs from pull request most recent head e3ebb54. Consider uploading reports for the commit e3ebb54 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #212 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 22 22 Lines 2062 2074 +12 Branches 236 239 +3 ========================================= + Hits 2062 2074 +12 ``` | [Impacted Files](https://codecov.io/gh/dfki-ric/pytransform3d/pull/212?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dfki-ric) | Coverage Δ | | |---|---|---| | [pytransform3d/rotations/\_\_init\_\_.py](https://codecov.io/gh/dfki-ric/pytransform3d/pull/212/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dfki-ric#diff-cHl0cmFuc2Zvcm0zZC9yb3RhdGlvbnMvX19pbml0X18ucHk=) | `100.00% <ø> (ø)` | | | [pytransform3d/rotations/\_conversions.py](https://codecov.io/gh/dfki-ric/pytransform3d/pull/212/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dfki-ric#diff-cHl0cmFuc2Zvcm0zZC9yb3RhdGlvbnMvX2NvbnZlcnNpb25zLnB5) | `100.00% <100.00%> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dfki-ric). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dfki-ric)

:umbrella: View full report at Codecov.
:loudspeaker: Do you have feedback about the report comment? Let us know in this issue.