Checking whether given type can be used for mesh indices or image data
was always done like this, because it was also needed to get OpenGL type
ID for the type:
TypeTraits<typename TypeTraits<T>::IndexType>::glType()
This was cumbersome, now the check is done using function, which
returns the OpenGL type ID directly:
TypeTraits<T>::indexType()
Also replaced TextureType with imageType() and renamed glType() to just
type().
Fuzzy comparison is implemented only on floating-point types with
type-specific epsilon, on integral types classic operator== is used.
TypeTraits class is now extension of Math::TypeTraits (where it makes
sense).