Implement V-extension once standardized

[fwsGonzo]

Vector instructions might give a boost in some scenarios, although I don't personally need them for anything I do. The emulator is not a very good number cruncher to begin with, but it will be interesting to see what vector instructions can offer. We could in theory support two sizes: One 128-bit vector and another 512/1024/2048-bit vector just to try to amortize the cost of instructions.

[fwsGonzo]

I have implemented a few vector instructions, and it's working great. Memory operations are much faster.