Compliation fixes for recent versions of MSVC++

These fixes allow the project to be compiled with Microsoft Visual Studio 2010, 2012 and 2013. I also enabled SIMD support on x64 processors under MSVC++.

One change I did not include, but should be considered, is enabling IO_USE_SIMD by default on Microsoft compilers by changing line 10 of UArray_math.c to be ```#if defined(__APPLE__) || defined(_MSC_VER)```. Most people using MSVC++ will be compiling for x86 or x64. There are older (and possibly unsupported) toolchains for other architectures, but in that case it would just default to the SIMD emulation.