After moving to Tcell and implementing its screen diff updates, we can
no longer watch STDOUT to get frames during integration tests. Instead
we need to use Tcell's SimulationScreen and which has a GetContents()
method. This is actually also a much more robust way of being able to
see what Browsh actually outputs during testing.
In the endless struggle to squash a Travis-specific bug, we now have
screenshots. Currently the screenshots are of the custom block font
state, so you can't read the text. But I'm planning on changing the
default state of the page to use a normal font - such that the
frame builder needs to toggle the block font on to build a frame. This
will make it more likely that screenshots will contain actual text.
Using mirrors in Dockerfile because default ones were down at
time of writing.
Refactor all build commands into 1 RUN command to try and reduce
the number of cached build layers and thus reduce the size of
the finished image.
