Added VS C++ 2010 project files to compile NengoUtilsGPU libraries.

Modified c files in NengoUtilsGPU folder to adhere to VS C++'s strict C coding style (needs to have all variable declarations before any of the running code).

WeightedCostApproximator.java - Updated import error message for NengoUtilsGPU library. Made it more detailed to match NengoGPU library import error.

NEFGPUInterface.java - Fixed slight issue with the error message. Will now display proper error message.