A colorful modal hex editor.

Features:
 - Color-codes bytes by value
 - Modal, selection-first editing inspired by Kakoune and Helix
 - Multiple selections, with the ability to split into N-byte chunks
 - Undo / redo
 - Inspects the current selection as signed, unsigned, binary,
   fixed-point, UTF-8 or color
 - Marks notable offsets and jumps to selected offset