Timer overlay + chrome take two

The Chrome support added in 0.1.0 stopped working with the release of Chrome 66. I swapped out the library I was using (chromedp) for a new one (godet). That seems to have done the trick and I like the interface of godet better for this use case.

Also, I have added the first pass at injecting a CSS overlay onto webpages to give a hint to the viewer as to when the content might be about to change. Try it out by setting timeroverlay=true in the configuration file.

Signed binaries are available here: https://dl.equinox.io/darrell_golliher/gotator/stable