python => python2 in development/ and tests/ and some dev scripts

If you want to run this on debian (which as far as i know is pretty much
the only problematic distribution here), you should be accustomed to the
change necessary by now.
python => python2 in main python files (run_uh and server)

Not including mac setup and build files.
Remove shebangs from files in tests/

Running them directly allegedly doesn't do much.
Fix #2065. Remove extension from filename

for quick- and autosavegames.
Fixes #2068 - Remove same version only checkbox in multiplayer menu
Update changelog.
Insert newline at the end of warehouse.yaml
Correct a docstring
Move popup code from window manager into separate class
Remove show_dialog from window manager

The manager doesn't need to know how to build dialogs from pychan
widgets, the Dialog class can do that.
Repair update notification on startup
Make all popups modal

I missed the savegame popup when removing the modal option from window
manager's popup code.
Remove unused attribute in Dialog

Because it looked like a spelling mistake, attempts were made to rename
the attribute to return_events (without leading underscore).

This however broke a lot of code, because popups used to set the return
events as class attributes. 'self.return_events = {}' in the class'
__init__ shadowed the class attribute which led to an empty dict.

The recent change that moved the popup code into a Dialog subclass
removed this problem (because return_events are set up in prepare),
removing this obsolete attribute is still the correct thing to do.
Update AUTHORS.md

My name had been written in section Swedish translators, though I've translated in Finnish -> I fixed that
Merge pull request #2076 from alluk/patch-1

My name had been written in section Swedish translators, though I've translated in Finnish.
Shorten a widget name

Markup reasons in guitranslations.
Update credits (#2076)
tests: Fix chat dialog gui test

Dialogs need special handling in gui tests. :/
Reword F10 description (@otinn)
Remove unused flags (of questionable use), clarify comments