Improved kernel memory usage

Moved base linear address to 0xFF800000
Kernel only reserves the page frames it actually needs
Memory for multiboot2 headers is freed
Video memory and APIC registers are dynamically mapped into linear addresses

include/pageallocator.h

@@ -72,4 +72,4 @@ size_t free_page_count(struct page_stack_t *stack);
  * @param stack 
  * @param map 
  */
-int initialize_page_stack(struct page_stack_t *stack, struct memory_map_t *map, size_t page_size);
+int initialize_page_stack(struct page_stack_t *stack, struct memory_map_t *map);

include/stdio.h

@@ -2,6 +2,8 @@
 
 #include <stdarg.h>
 
+int initialize_screen();
+
 int putchar(int c);
 
 int puts(const char *str);