Add user configuration

[Mauritz8]

The user should be able to configure certain behavior, such as:

• Ability to change keybindings.
• Decide how file paths should be displayed. Options could include:
  • only display the file name, not the path.
  • truncate the start of the path if the whole path doesn't fit.
  • show the filename first followed by the path
  • only display the first character of each directory in the path.
• Decide if filetype icons should be displayed. A user might not want to see filetype icons even if they have an icon plugin installed. It could be that they only want icons for a specific plugin.