cgi/h: redefine CGI::url_param()
cgi/h: adding graph_ext url param
cgi/h: only add the dump when dump=1
Merge branch 'devel' of github.com:munin-monitoring/munin into devel

* 'devel' of github.com:munin-monitoring/munin:
  cgi/h: be able to have SVG as images
  cgi/h: Avoid emitting DUMP by default
  t: the use_node_name has changed its meaning