Use SSE2 in debug and x64, not just x86.

Apples to apples is nice.  More accurate floats in debug is bad.
Disasm transposed vectors properly.
Fix jit VDot mapping vd incorrectly to a quad.
Respect the writemask in VDot.

Although it's basically a no-op in that case...
Add a flag for eating prefixes to the MIPS tables.

Still incomplete, just filled in ones I've tested so far.
Automatically eat prefixes in x86 jit.

Simplifies the code and makes it easier to know they're eaten
even for ops not yet jitted.
Re-enable vdot and vadd/etc. in x86 jit.
Mark more instructions that eat prefixes.
Add more temp regs, allow swapping if necessary.
Preserve orig regs when applying vfpu prefixes.
Use prefixD directly in jit, just like interp now.
Handle temp regs better, no need for direct access.
Make applying prefixes mostly automatic.

And implement (hopefully) D prefixes.
Support known prefixes in the vfpu jit.
Merge pull request #728 from unknownbrackets/jit-vfpu

Fix and re-enable vdot again on x86
Try to reuse temp regs for better caching.
Merge pull request #729 from unknownbrackets/jit-vfpu

Jit known prefix support
Assume prefixes start default until proven wrong.

Currently this means nothing since the MIPSTables flags are wrong.
It will blow the cache once, after the first vfpu op.
Add a MIPSTables flag for ignoring the prefix.
Merge pull request #730 from unknownbrackets/jit-vfpu

Assume prefixes start as default until proven wrong