shellcraft.mov does not support AH, BH, etc. registers

[david942j]

from pwn import *
# context.arch = 'i386'
print shellcraft.mov('eax', 'ah')

Expected:
movzx eax, ah

Result:

NameError: name 'ah' is not defined

The error is raised when trying to eval ah as a system-constant value

But the real reason is ah is not defined in shellcraft/registers.py as a register in i386.

Issue occurs in amd64 as well.

[zachriggle]

I don't think we support the xh registers since they complicate some of the logic. If you can submit a pull request that adds the functionality, and some doctests for various permutations (e.g. mov("ah", "al")) we can get this included.