Implement sort ordering of notes
Don't open a note with no title
Refactor of noetwidget display attribute handling

Just a small refactoring to avoid having to wrap NoteWidgets in AttrMaps
and then use .base_widget to get at the NoteWidget.
Show placeholder text in search bar when empty
Put a line box around the search box

and also put some padding around the list box so the text lines up with
the search box's text
Make ctrl x quite the app, like nano
Add placeholder texts in note list
Update TODO
Add command-line interface in terminal_velocity.py
Put back padding on note list

Accidentally broke the padding in a previous commit
Update TODO
Handle ~ in note dirs in config file