Correctness issues:

- some eflags manipulation incorrectly reset the bit 0x2.
- SVM: test, cpu save/restore, SMM save/restore. 
- x86_64: lcall/ljmp intel/amd differences ?
- better code fetch (different exception handling + CS.limit support)
- user/kernel PUSHL/POPL in helper.c
- add missing cpuid tests
- return UD exception if LOCK prefix incorrectly used
- test ldt limit < 7 ?
- fix some 16 bit sp push/pop overflow (pusha/popa, lcall lret)
- full support of segment limit/rights 
- full x87 exception support
- improve x87 bit exactness (use bochs code ?)
- DRx register support
- CR0.AC emulation
- SSE alignment checks
- fix SSE min/max with nans

Optimizations/Features:

- add SVM nested paging support
- add VMX support
- add AVX support
- add SSE5 support
- fxsave/fxrstor AMD extensions
- improve monitor/mwait support
- faster EFLAGS update: consider SZAP, C, O can be updated separately
  with a bit field in CC_OP and more state variables.
- evaluate x87 stack pointer statically
- find a way to avoid translating several time the same TB if CR0.TS
  is set or not.
