Taskplot cleanup

Minor cleanup in [i]plot_task.py

• fix in documentation that iplot_task needs python2. Runs fine in python3.
• expanded FULLTYPE list to contain recently added task types
• moved FULLTYPE and assiciated stuff such as colour assignment to swift_hardcoded_data.py to avoid code duplication

assigned to @matthieu

assigned to @pdraper and unassigned @matthieu

added python label

requested review from @matthieu

approved this merge request

Thanks, looks good for me.

mentioned in commit 950ca728

merged