Panel in UI to show currently running processing scripts

[rambaut]

We need a panel which shows currently running processing scripts started using the script button for each channel. This could show progress and text messages (these are already picked up by the PipelineRunner class). A kill button on these would also be good.

The script option on the individual channels should probably be disabled when running (or the text could change to show 'running' and it takes you to the progress panel instead).

[jameshadfield]

Now working, although UI tweaks will be needed.

[rambaut]

Reopening it because this is cool but not what I mean. We need a panel which shows any postprocessing scripts that are running, one per line with a progress indicator (or a spinning thing to indicate running) and a kill button.