- Custom line iterator code for file loading, because rust's built-in one
  only recognizes LF and CRLF.
- Line number display
- Line wrapping
- File opening by entering path
- UI that wraps editors, for split view.
- Persistent infinite undo
- Multiple cursors
- "Projects"
- Move undo/redo functionality into Editor instead of Buffer

- Clean up text buffer interface:
    - //Editing (these are undoable):
        - //insert_text
        - //remove_text_before
        - //remove_text_after
        - //move_text
    - Undo functionality:
        - //Undo
        - //Redo
        - Edit transactions (for composite edit operations)
    - Info:
        - byte_count
        - //grapheme_count
        - //line_count
    - Position conversions:
        - //index -> line_col
        - //line_col -> index
        - //index -> vis_2d
        - //vis_2d -> index
        - index -> byte_index
        - byte_index -> index
    - Reading text:
        - //grapheme at index (includes visual width in return)
        - //Grapheme iterator (useful for search code, etc.)
        - Byte iterator (useful for search code, etc.)
        - Reverse byte iterator (useful for search code, etc.)
        - //Line iterator (useful for display code)