feat(vector2): add initial vector2 implementation

[fallenoak]

Closes #56

[codecov]

Codecov Report

Merging #57 into master will increase coverage by 0.04%.
The diff coverage is 98.38%.

@@            Coverage Diff             @@
##           master      #57      +/-   ##
==========================================
+ Coverage   97.83%   97.88%   +0.04%     
==========================================
  Files           6        7       +1     
  Lines         646      708      +62     
  Branches       79       89      +10     
==========================================
+ Hits          632      693      +61     
- Misses         14       15       +1     

Impacted Files	Coverage Δ
src/lib/Vector2.mjs	98.38% <98.38%> (ø)

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