tests/test-config-env.py.out

paper: make actual changeset entries have backgrounds on /graph

This patch removes a separate container for backgrounds only and puts
backgrounds on changeset elements themselves. This makes it so that JS code
doesn't need to create background elements separately anymore.

There's a bit of manipulating positions of elements: every changeset entry has
a "fg" element that gets a higher z-index than <canvas> element. This
prioritizes text information, so that even if it somehow gets close to the
graph drawn on <canvas> (which has z-index of 5), it'll still be on top of it.
This can happen if commit message has a long first line and browser window is
narrow, for example.

pager.pager=p0 # $TESTTMP/sysrc:4
ui.editor=e1 # $TESTTMP/userrc:2

pager.pager=p2 # $PAGER
ui.editor=e1 # $TESTTMP/userrc:2