Fixing things for Linux

Here are some more changes to make things work cross-platform. You are right that we do need to parse the link line differently for Linux. At some point, I did have this in the script, but it got deleted somehow and it actually does build (apparently) correctly without any libraries listed in Linux. You don't get an error until you try to import (which I didn't do). I fixed up the mechanism for making the library list now and finally did make it depend (a little) on the OS, although this could probably be avoided in the end, since you can tell from the link line whether you are in windows or not. I looked into the problem with the MSVC++ compiler a bit more and I see now that what you had was legal C++, but just not allowed in MSVC++ for some reason (See, e.g., http://stackoverflow.com/questions/16461265/ctor-is-not-a-member-of-baseclass). I think the solution is just to explicitly call the base class method inside the derived class method, which seem to work fine. One of the commits below is to reorganize things to make the setup script work more straightforwardly, as I suggested in my e-mail yesterday. Feel free to reject this way of doing things or suggest some other way. It is just what is working for me now and I don't have a lot of time to play with it. Hope these are helpful.