Added some Emacs-style actions
Added options for the following keybindings:
- Jump to start/end of line
- Move to next/previous line
- Insert line below the cursor
If jump to start of line is activated when the cursor is already there, the cursor will instead move to the first non-space character on the current line.
There are no menu items for these, because that wouldn't make much sense anyways. Not bound to any keys by default.