Add complexity counter per author

[adam-waldenberg]

Add a complexity counter to each author. This is an idea to add functionality to gitinspector to track the "average" complexity of the code commited by an author. This would help in giving us an indication of what kind of code an author has added. This would have to rely heavily on regexp in order to analyze statements and statement depth.

The source of the idea comes from the paper;
https://softwareprocess.es/pubs/feist2016VISSOFT-syntax-tree.pdf

Instead of tracking the AST, like the paper suggests, the idea is to track complexity of lines (depth, type of statement and other factors).

Should this information be tracked on the surviving lines only or on all the lines commited over time by an author ?