Features/spin bivector

[brainandforce]

This adds a new SpinBivector type that represents a spin plane. This can be useful when working with spin planes noncollinear to a lattice direction.

[brainandforce]

I really don't understand this:

Ambiguity #5
getindex(a::StaticArraysCore.StaticArray, ::Colon) @ StaticArrays ~/.julia/packages/StaticArrays/yXGNL/src/indexing.jl:104
getindex(b::Electrum.SpinBivector, i...) @ Electrum ~/work/Electrum.jl/Electrum.jl/src/data/spin.jl:94

Possible fix, define
  getindex(::Electrum.SpinBivector, ::Colon)

because this ambiguity doesn't exist for Electrum.LatticeBasis

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (94a3884) 60.16% compared to head (668e1de) 61.06%.

Files	Patch %	Lines
src/data/spin.jl	92.68%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #205      +/-   ##
==========================================
+ Coverage   60.16%   61.06%   +0.89%     
==========================================
  Files          21       21              
  Lines        1446     1487      +41     
==========================================
+ Hits          870      908      +38     
- Misses        576      579       +3     

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