Minor fix for brace highlighting
Add temporary patch for Scintilla on older Gtk versions
Improve external command input

Provide a more shell-like experience:

- complete partial parts entered,
- do an internal cd only once the navigation is done
- only complete directories for `cd`
- popup completion automatically only when deemed neccessary
Avoid an extra empty line for a finished process buffer
Process buffer: Self-close when there's no output

Since sometimes you just want to issue silent one-off
commands, e.g. mkdir etc.
Fix incorrect length calculation

Fixes #33.
Move global commands out of the editor sub keymap
Add binding.binding_for

For finding a binding for a particular action.