Complete SSE instruction definitions for x86-64

* New instruction formats:
  - 2-byte instructions with GP/mem source and XMM destination.
  - 1- and 2-byte instructions with XMM source and GP/mem destination.
  - 1- and 2-byte instructions wit GP/mem source and GP destination.

* Complete support for SSE instruction sets:
  - SSE3
  - SSSE3
  - SSE4.1
  - SSE4.2

* Fix definition of pblendvb, blendvps, blendvpd: These require a third operand,
  implicitly in XMM0.