adding mAP metric

[jshermeyer]

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Fixes # (issue)

Type of change

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How Has This Been Tested?

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• [x] My PR has a descriptive title
• [x] My code follows PEP8
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[codecov[bot]]

Codecov Report

Merging #394 into dev will increase coverage by 0.30%. The diff coverage is 94.91%.

@@            Coverage Diff             @@
##              dev     #394      +/-   ##
==========================================
+ Coverage   56.16%   56.46%   +0.30%     
==========================================
  Files          81       81              
  Lines        6930     6983      +53     
==========================================
+ Hits         3892     3943      +51     
- Misses       3038     3040       +2     

Impacted Files	Coverage Δ
solaris/eval/vector.py	87.89% <94.73%> (+2.01%)	:arrow_up:
tests/test_eval/vector_test.py	100.00% <100.00%> (ø)
solaris/nets/transform.py	62.90% <0.00%> (+0.80%)	:arrow_up:

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