Add statistics tracking

[epi052]

closes #179
closes #176
closes #177

Landing a Pull Request (PR)

Long form explanations of most of the items below can be found in the CONTRIBUTING guide.

Branching checklist

• There is an issue associated with your PR (bug, feature, etc.. if not, create one)
• Your PR description references the associated issue (i.e. fixes #123456)
• Code is in its own branch
• Branch name is related to the PR contents
• PR targets master

Static analysis checks

• All rust files are formatted using cargo fmt
• All clippy checks pass when running cargo clippy --all-targets --all-features -- -D warnings -A clippy::deref_addrof
• All existing tests pass

Documentation

• New code is documented using doc comments
• Documentation about your PR is included in the README, as needed

Additional Tests

• New code is unit tested
• New code is integration tested, as needed
• New tests pass

[codecov]

Codecov Report

Merging #168 (62efbe3) into master (0c29f3d) will increase coverage by 0.41%.
The diff coverage is 95.90%.

@@            Coverage Diff             @@
##           master     #168      +/-   ##
==========================================
+ Coverage   93.96%   94.38%   +0.41%     
==========================================
  Files          14       14              
  Lines        3117     3439     +322     
==========================================
+ Hits         2929     3246     +317     
- Misses        188      193       +5     

Impacted Files	Coverage Δ
src/scan_manager.rs	88.33% <90.38%> (-0.73%)	⬇️
src/main.rs	91.79% <90.69%> (-0.97%)	⬇️
src/statistics.rs	95.32% <95.32%> (ø)
src/scanner.rs	92.74% <98.86%> (+0.70%)	⬆️
src/banner.rs	100.00% <100.00%> (ø)
src/config.rs	97.13% <100.00%> (+0.04%)	⬆️
src/extractor.rs	96.13% <100.00%> (+1.13%)	⬆️
src/heuristics.rs	92.12% <100.00%> (+0.96%)	⬆️
src/progress.rs	100.00% <100.00%> (ø)
src/reporter.rs	90.56% <100.00%> (+1.09%)	⬆️
... and 2 more

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