Support for VS2013 and future versions

[cameni]

In the current version (0.9.4.5) the compiler detection code in setup.hpp assigns GLM_COMPILER to be GLM_COMPILER_VC for any unknown _MSC_VER. For Visual Studio 2013 preview this then uncovers an error in _detail.hpp:476 in macro:
#define GLM_ALIGNED_STRUCT(x)
(missing 'struct')

Even though this is the thing that makes GLM fail to compile on VS2013, it would be good to alter the compiler detection so that any newer than known _MSC_VER compiler version sets the GLM_COMPILER to the latest known version.

[Groovounet]

This bug is fixed and GLM_COMPILER will be set to the latest known compiler version. That will ensure longer life of GLM releases.

These changes have been applied to GLM 0.9.4 branch.

Thanks for contributing,
Christophe