(partial) msvc support

[Zoadian]

some changes to support compilation with msvc120
I used .h and .cc files directly without cmake.

also line 2374 is probably wrong

so this is just the first step to support msvc.

[coveralls]

Coverage remained the same at 100.0% when pulling 90865cc on Zoadian:master into c4d7485 on nlohmann:master.

[nlohmann]

Hi @Zoadian, sorry for not answering earlier. Though I like the idea of having a Windows version, I am currently working on new code that uses even more C++11 features. When I look at your code, I see that you mostly use the preprocessor to exclude those parts that are not yet supported by Visual Studio. I think I would rather wait until Visual Studio has true C++11 support rather than to fragmentize the project like this - in the end, I am using this project to learn the new C++11 features.

I'm going to close the pull request here, but I would be happy if you would host a Windows-compatible version yourself. I would link to it in the README. You might also want to get in touch with @kirkshoop. Kirk opened a similar pull request #29 earlier.

[nlohmann]

Oh, I forgot. The error you mentioned is indeed a mistake. I will fix it soonish.