Add mAP evaluation for COCO and VOC datasets

[zhiqwang]

Closes #59

• Fix the dataset pipelines
• Support mAP metrics computing on COCO datasets
• Support mAO metrics computing on VOC datasets

[codecov]

Codecov Report

Merging #70 (e6a2c45) into master (2332a2c) will decrease coverage by 1.44%.
The diff coverage is n/a.

❗ Current head e6a2c45 differs from pull request most recent head 4c5b67f. Consider uploading reports for the commit 4c5b67f to get more accurate results

@@            Coverage Diff             @@
##           master      #70      +/-   ##
==========================================
- Coverage   81.79%   80.35%   -1.45%     
==========================================
  Files           8        8              
  Lines         736      682      -54     
==========================================
- Hits          602      548      -54     
  Misses        134      134              

Flag	Coverage Δ
unittests	80.35% <ø> (-1.45%)	⬇️

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Impacted Files	Coverage Δ
test/test_models.py	93.15% <0.00%> (-1.33%)	⬇️
test/test_onnx.py	86.58% <0.00%> (-1.20%)	⬇️
test/test_torchscript.py	97.43% <0.00%> (-0.57%)	⬇️

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[zhenwang23]

Hi Zhiqiang, Nice to meet you. Wanna talk about new opportunities?

[zhiqwang]

@zhenwang23 - Nice to meet you too, Let's discuss about these via Email, and I have already replied to you, please check your email.

[zhiqwang]

Duplicate of #89