Move coloring logic into the hpp functions so that each value can
be colored independently.  It'd required for event group view.

For overhead column, add a callback for printing 'folded_sign' of
callchains of a hist entry.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1358845787-1350-11-git-send-email-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>