Major update

- Add an IO system to hijack a bit of the terminal.
- Other minor fixes.

include/definitions.h

@@ -14,5 +14,18 @@ struct ed_error : std::runtime_error {
   ed_error(std::string msg) : std::runtime_error(msg) {}
 };
 
+struct Highlight {
+  enum : uint8_t {
+    None = 0,
+    Bold = 1 << 0,
+    Italic = 1 << 1,
+    Strikethrough = 1 << 2,
+    Underline = 1 << 3,
+  };
+  uint32_t fg;
+  uint32_t bg;
+  uint8_t flags;
+};
+
 struct BEd;
 } // namespace bed