Autopep8
Some manual fixes for Flake8
cleanup: calendar_display_test (also: tests!)

will soon be integrated into a new common module for all terminal
interface related stuff
removed status leftovers
setup: better version number generation
moved some functions to terminal.py
minimal code deduplication
code moved from controller to terminal (also tests!)
minor bugfix
renamed local_timezone -> local_tz

The same goes for default_timezone, but not in the config file yet.
This was just an inconsistent mess (and partly still is because of the
config file).
local variables renamed
Calendar.delete and change_collection work

Also some tests for Calendar and better documentation for Event