Add a way to see the history of a single file in Pure Git

[svenvc]

Given a file under git control, return all the commits that changed it backwards in history and show how each commit changed it (i.e. the diff).

Allow the model to be used for further analysis.

[seandenigris]

It would be great if this worked across renames

[svenvc]

Haha, Sean, always finding the sore spots ;-)

We'll see, first the simple most common case.

Theoretically the model is enough even now to do that manually but that would be a very slow commit walk.

The current version relies on git itself to do the filtering because that is way faster.

I will check how it deals with renames.

[svenvc]

The files view now sends into a PureGitFile object, representing the state and evolution of a specific tracked file in the repository.

[svenvc]

The history views show commits restricted to a specific path. Those commits are PureGitFileCommit instances which are subclasses of PureGitCommit restricted to that specific path so they can show only the changes to that path, or the contents at that point in time.