fix signal bug in chat widget for older PyQt versions
fixed error icons for Windows
PyInstaller master build should run on Mac again (issue #214)
Merge branch 'master' into nightly

Conflicts:
	lunchinator/gui_elements/error_message_dialog.py
	plugins/plugin_repositories/add_repo_dialog.py
	plugins/private_messages/chat_widget.py
	plugins/private_messages/message_item_delegate.py