Improve highlighting structure

- switched to a sparse delta based map
- true lazy-loading to avoid any unneccessary allocations
- fixed windows management api

src/io/renderer.cc

@@ -1,15 +1,19 @@
 #include "io/sysio.h"
 
+namespace io {
 std::vector<ScreenCell> new_screen;
-static uint32_t rows, cols;
-static bool show_cursor = 0;
-static std::vector<ScreenCell> old_screen;
-static termios orig_termios;
+uint32_t rows, cols;
+bool show_cursor = 0;
+std::vector<ScreenCell> old_screen;
+termios orig_termios;
+} // namespace io
+
+using namespace io;
 
 void disable_raw_mode() {
   std::string os = "\x1b[?1049l\x1b[2 q\x1b[?1002l\x1b[?25h\x1b[?2004l";
   write(STDOUT_FILENO, os.c_str(), os.size());
-  if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &orig_termios) == -1) {
+  if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &io::orig_termios) == -1) {
     perror("tcsetattr");
     exit(EXIT_FAILURE);
   }
@@ -45,8 +49,6 @@ Coord start_screen() {
 
 void end_screen() { disable_raw_mode(); }
 
-Coord get_size() { return {rows, cols}; }
-
 void io_render() {
   static bool first_render = true;
   uint32_t current_fg = 0;