add 2d rotation_angle

[jw3126]

No description provided.

[codecov-io]

Codecov Report

Merging #92 into master will decrease coverage by 15.02%.
The diff coverage is 71.42%.

@@             Coverage Diff             @@
##           master      #92       +/-   ##
===========================================
- Coverage   86.99%   71.97%   -15.03%     
===========================================
  Files           9        8        -1     
  Lines         746      735       -11     
===========================================
- Hits          649      529      -120     
- Misses         97      206      +109

Impacted Files	Coverage Δ
src/core_types.jl	74.22% <71.42%> (-12.51%)	⬇️
src/util.jl	40% <0%> (-50%)	⬇️
src/derivatives.jl	40.9% <0%> (-45.46%)	⬇️
src/quaternion_types.jl	52.99% <0%> (-42.74%)	⬇️
src/angleaxis_types.jl	71.95% <0%> (-20.74%)	⬇️
src/principal_value.jl	83.33% <0%> (-12.5%)	⬇️
src/euler_types.jl	83.52% <0%> (-0.97%)	⬇️
src/Rotations.jl

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[tkoolen]

Makes sense to me.

[tkoolen]

Sorry, some more comments.

Could you update this comment:

https://github.com/FugroRoames/Rotations.jl/blob/a5b1635fc78934fce5648c7b0cb5670867db69df/src/Rotations.jl#L34

and restrict these methods:

https://github.com/FugroRoames/Rotations.jl/blob/a5b1635fc78934fce5648c7b0cb5670867db69df/src/core_types.jl#L16-L17

to Rotation{3}?

[tkoolen]

Great, thanks!

[tkoolen]

JuliaLang/METADATA.jl#21218