Fix msvc and xcode generators

[uilianries]

• Update some points to work with python3 on Windows and OSX

[SSE4]

I think it's better to make required changes into our fork https://github.com/bincrafters/gyp

[uilianries]

@SSE4 should we create a new tag ?

[SSE4]

@uilianries yes, it would be nice

[uilianries]

now we have two options,

remove all branches related to 20171101 and distribute only 20181120

or, add an error condition to 20171101 for msvc and osx

WDYT @SSE4 ?

[SSE4]

@uilianries just remove old, I don't think they are very frequently used

[uilianries]

@SSE4 this will require removing the package as well

[SSE4]

I don't think it's a problem
also, we need to create latest alias (like for msys2_installer)
AFAIK the only project using it is https://github.com/bincrafters/conan-libuv, which has to be updated

[uilianries]

@SSE4 nice, I'm gonna remove it