doing some memory work and gdt and timer and vga

kernel/vga.c

@@ -0,0 +1,9 @@
+#include "vga.h"
+
+uint8_t vga_entry_color(vga_color fg, vga_color bg) {
+    return fg | bg << 4;
+}
+
+uint16_t vga_entry(unsigned char uc, uint8_t color) {
+    return (uint16_t)uc | (uint16_t)color << 8;
+}