Add line numbers for metrics in Cyclomatic and Halstead operators

[devdanzin]

As a first step to address #217, allowing wily to generate annotated source listings with inline visualization of code metrics, we need to record line numbers for code blocks when building the cache.

Radon already supplies line numbers (lineno and endline) for Cyclomatic Complexity, so we just record those in the detailed metrics.

For Halstead line numbers, we need to customize visitor, harvester and some other pieces. PRs and issues upstreaming this work have already started being submitted to radon.

This PR is necessary regardless of whether the annotate feature lands as a command or is kept as a separate tool.

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.09% 🎉

Comparison is base (dbe9172) 95.76% compared to head (fd71462) 95.86%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #218      +/-   ##
==========================================
+ Coverage   95.76%   95.86%   +0.09%     
==========================================
  Files          25       25              
  Lines        1370     1403      +33     
  Branches      293      296       +3     
==========================================
+ Hits         1312     1345      +33     
  Misses         33       33              
  Partials       25       25              

Files Changed	Coverage Δ
src/wily/operators/cyclomatic.py	100.00% <ø> (ø)
src/wily/operators/halstead.py	95.58% <100.00%> (+4.15%)	⬆️

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[tonybaloney]

Please update one of the tests to verify this behaviour

[devdanzin]

Thanks for reviewing this!

I couldn't find a test that covered similar behavior, so I created on that checks all metric fields and values from the cache. I'm not sure it's in the best place, maybe it'd be better as a separated test file?

Writing the test uncovered two issues:

• The code adding line numbers doesn't work with Python 3.7 (disabled on 3.7).
• The typing of HalsteadOperator._report_to_dict() was wrong (fixed).