Adds support for aggregated graphs + patch title

[ThomasTNO]

This pull request implements aggregated graph support for directories.

It also patches a bug in title creation.

[tonybaloney]

Thanks! Please can you add a basic test in https://github.com/tonybaloney/wily/blob/master/test/integration/test_graph.py

[codecov-commenter]

Codecov Report

Merging #138 (f99d09d) into master (e72b7d9) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #138   +/-   ##
=======================================
  Coverage   97.82%   97.83%           
=======================================
  Files          23       23           
  Lines        1152     1153    +1     
=======================================
+ Hits         1127     1128    +1     
  Misses         25       25           

Impacted Files	Coverage Δ
src/wily/__main__.py	98.31% <100.00%> (+<0.01%)	⬆️
src/wily/commands/graph.py	100.00% <100.00%> (ø)

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[ThomasTNO]

Thanks! Please can you add a basic test in https://github.com/tonybaloney/wily/blob/master/test/integration/test_graph.py

Added two basic tests

[ThomasTNO]

Attempted to patch the labels of data points, but it still seems bugged.

[ThomasTNO]

Attempted to patch the labels of data points, but it still seems bugged.

Should be working properly now.