* Hide zero values for throughput, backlog and delays graphs
Relates to ISSUE #288
* New function `array_to_zero` to reduce repetition.
* Transform zero values to `null` in Y value arrays for the
throughput, backlog and delay graphs on circuit_info.html
* Also change tin labelling to match the "backlog" graph on
Delays.
* Reduce marker size.
* Scale displayed/graphed queue delays to ms
References ISSUE 288
Scale the delays graph entries, which are apparently in usec, to
ms.
cf41b47b77
