gitweb: plug followlines UI in filerevision view
Mostly copy CSS rules from style-paper.css into style-gitweb.css. The only
modification is addition of !important on "background-color" rule for
"pre.sourcelines > span.followlines-selected" selector as the background color
is otherwise overriden by "pre.sourcelines.stripes > :nth-child(4n+4)" rule.
gitweb: handle "patch" query parameter in filelog view
As for paper style, in
f36dc643ffdc, we display "diff" data as an additional
row in the table of revision entries for the gitweb template.
Also, as these additional diff rows have a white background, they may be
confused with log entry rows ("age", "author", "description", "links") of even
parity (parity0 also have a white background). So we disable parity colors for
log entry rows when diff is displayed and fix the color to the
"dark" parity (i.e. parity1 #f6f6f0) so that it's always distinguishable from