Transition to cmake on Windows

[tigerw]

Ox and O2 are almost identical. They differ only in the fact that O2 also throws GF and Gy. There is almost no reason to avoid throwing these two switches.

/GF is great - it pools all identical string literals in a read-only memory region. So if you have some literal in multiple areas of code you'll only have it once in the executable which reduces the image size. And if your code attempts to modify it you'll get Access Violation which protects you against dumb errors.