Print more info from Jinja2 exception.
#1200: fix startup_task:finish dependency
This fixes removing a task via a reload.

It adds a test and a fix.
Merge pull request #1207 from benfitzpatrick/1200.back-comp-startup-or

Fix startup_task:finish dependency
Addressed review feedback.
Briefer comment.
Merge pull request #1208 from benfitzpatrick/fix-reload-remove-task

This fixes removing a task via a `cylc reload`.
gcylc: update family hierarchy in case of reload.
Added a test to insert a task added by a reload.
PEP 8 for previous commit.
Merge pull request #1205 from hjoliver/1203.better-Jinja2-errors

Print more info from Jinja2 exceptions
Merge pull request #1209 from hjoliver/gcylc.fix-task-added-by-reload

gcylc: fix task added by reload
A bug fix for the cylc-submit tests.
Merge pull request #1210 from hjoliver/tests.bug-fix

A bug fix for the cylc-submit tests.