add Equal tolerance method to Quaternion

[adlarkin]

Signed-off-by: Ashton Larkin ashton@openrobotics.org

🎉 New feature

Summary

I've added a method to compare equality between quaternions with a user-defined tolerance, similar to the Vector3 class. This is useful in cases where the default precision of the quaternion's == operator (.001) isn't enough, such as in gazebosim/gz-physics#223 (since physics requires high precision, 1e-6 is used for equality tolerance instead of 1e-3).

Test it

Take a look at the unit tests written in this PR (files changed tab -> src/Quaternion_TEST.cc).

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

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[codecov]

Codecov Report

Merging #196 (1e9ce65) into ign-math6 (6f4dcfa) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@              Coverage Diff              @@
##           ign-math6     #196      +/-   ##
=============================================
- Coverage      99.20%   99.20%   -0.01%     
=============================================
  Files             63       63              
  Lines           6020     6019       -1     
=============================================
- Hits            5972     5971       -1     
  Misses            48       48              

Impacted Files	Coverage Δ
include/ignition/math/Quaternion.hh	100.00% <100.00%> (ø)

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[azeey]

LGTM!