Implementing diagram representation for workflows

[Buddhima]

Summary of Changes

This implementation adds diagram representation of a workflow. A sample diagram ins as follows (taken from Joomla! Default workflow:

This implementation uses following color indexing:
green - Published condition states
red - Trashed condition state
yellow - Unpublished condition states

This should actually go into a separate template in tmpl\workflow folder. Unfortunately because an error in tab view (should be fixed in core), this is added after workflow description.

Testing Instructions

Create a workflow and add few states and transitions. Open the workflow's Description tab and scroll down.

[jjaracz]

There should be check-in if user creates workflow or not because we can not render diagram for workflows that does not have any transactions.

[Buddhima]

@jjaracz , Thanks for pointing out. Updated PR with check for new workflows.

[jjaracz]

I have a strange behavior, when I'm moving items then some transactions disappear.
Here is default view (when I'm refreshing website, default set)

When i change structure to see all of it (drag&drop states).

And here I'm showing that transactions disappear depends of states position.

I'm using:

• Kubuntu 17.04 x64 4.10.0-38-generic
• Firefox 56.0 / Chromium 62.0.3202.75

[Buddhima]

I have observed same behavior in Chrome on Windows too. Seems to be a limitation of JS library.