perf timechart: Group figures and add title with details

Add titles to figures so we can run SVG interactively in Firefox and
check event details in the tooltips.

This also aids exploring SVG with Inkscape because when user clicks on
one part of logical figure, all parts are selected.

It's also possible to read titles with Inkscape in the object details.

Signed-off-by: Stanislav Fomichev <stfomichev@yandex-team.ru>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1383323151-19810-6-git-send-email-stfomichev@yandex-team.ru
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>