Years per technology

[rimutaka]

This is something that has been overlooked from the beginning. The app counts LoC at the last commit and ignores everything that happened before that. It is not easy to fix. Ideally, the reports needs a histogram with monthly totals or increments, but that means reprocessing all repos and will dramatically increase the processing time.

1. add a crude estimate based on 1st / last contributor commit to the project which would need to be calculated on the server side
2. add first commit per file to start calculating a more accurate number of years per tech
3. add a breakdown of LoC changed per month per file to calculate a reliable aggregation

git log --numstat should have all the info needed to prepare the histogram.