Stick to a single config entry per option.

We don't need a bool in the ini AND an int setting.

This should also fix the anistropy setting, which appears to have been
pretty much broken.  Also makes frameskip enable even if you don't tap
auto, which is what I'd assumed it did before.
Merge pull request #1632 from unknownbrackets/config

Stick to a single config entry per option