This patch adds a PartAddressableRegister type, which divides a 32-bit
value into separate parts needed for the EAX/AX/AL/AH register splits.
Clean up the code around register access to make it a little less
cumbersome to use.
This introduces a new X86 CPU emulator for running SerenityOS userspace
programs in a virtualized interpreter environment.
The main goal is to be able to instrument memory accesses and catch
interesting bugs that are very hard to find otherwise. But before we
can do fancy things like that, we have to build a competent emulator
able to actually run programs.
This initial version is able to run a very small program that makes
some tiny syscalls, but nothing more.
