Adds pre-commit config to run various lintersci_improvements

This ads black, isort, pyupgrade, and flake8 to pre-commit-config.yaml
There are also some small changes to travis.yml and tasks.py to reduce
some repeated configurations that should be consolidated into
setup.cfg. Most other changes are automated by the linter scripts.

1 files changed, 1 insertions, 0 deletions

diff --git a/examples/event_loops.py b/examples/event_loops.py
index 53d3ca2b..86dc01fb 100755
--- a/examples/event_loops.py
+++ b/examples/event_loops.py
@@ -11,6 +11,7 @@ import cmd2
 
 class Cmd2EventBased(cmd2.Cmd):
     """Basic example of how to run cmd2 without it controlling the main loop."""
+
     def __init__(self):
         super().__init__()