Match scoring

[johnmhoran]

When we have a matching set of files in deltacode, we need to have some way of scoring or weighing a match.

This will also come into play more when we start to incorporate license and copyright changes.

This score will ultimately take the place of modified string in our match object.

[steven-esser]

A simple way to start is just by adding a new 'score' field to our Delta object.

After that, you can define a new function under the Delta object that computes the score, or update this field some other way.

Even though we do not do explicit calculations right now, we can hardcode score values for our different Delta categories as a start.

[steven-esser]

This has been handled in other tickets.