Fixed USE_IPV6 and USE_IDN not being passed
from Makefile.vc to MakefileBuild.vc
Fixed whitespace and formatting issues
Fixed typo and format in help message
This is a separate makefile for MSVC builds. It is deliberately put in
another dir than src/ and lib/ to allow a different build experience
than the previous - at least during a period. Eventually we should
unify.