Addressing inconsistencies in the dynamic rule matrix

Following up on https://github.com/gorhill/uBlock/issues/527#issuecomment-124918048, I threw together a quick/very dirty demonstration for gorhill to play with. For now I ignored the `image` type rule as I don't think it's as important in the context of the matrix.

Adding a yellow indicator for cells that have conflicting dynamic rules (e.g. 3p block & 3p-scripts allow) applied to them in the filtering matrix would resolve most inconsistencies and the confusion they cause.

The yellow indicator is already used for hosts that have some requests allowed and some denied in the first column of the matrix, so it would be intuitive to apply that to (at least parts of) the third column.

The commit is here: https://github.com/seanrand/uBlock/commit/8eefa9f64a00e8431e20dc07304efe149b20c82a (only tested in Chromium 48.0.2539.0, by the way)

Thoughts?

P.S., sorry for not following contributing.md but I hope the comment and commit is enough to get my point across as to why I think this would be an improvement.