Initial boot test

Simple boot test release

• Boots up
• Initialises GDT, IDT, page tables
• Scans memory map, ACPI, PCI
• Waits for key presses and shows scan codes in a loop

Currently compiled with -Onone due to a compiler assert with -O

To run under qemu:
$ bunzip2 boot-hd.img.bz2
$ qemu-system-x86_64 -hda boot-hd.img