paper: don't register click handlers with inline javascript (
issue5812)
The use of inline href="javascript:" undermines CSP policies that
don't allow inline javascript.
This commit changes the registering of the diffstat and line wrapping
toggle handlers to the the global DOMContentLoaded handler, thus
eliminating all inline javascript from the paper template.
Differential Revision: https://phab.mercurial-scm.org/D3437
#require docutils gettext
$ $TESTDIR/check-gendoc el
checking for parse errors