Allows applications to use templated types

[Groovounet]

In theory, applications are not supposed to use templated types as there are in the detail namespace. This is very inconvenient.

Move tvec* and tmat* to glm namespace.

[richardeakin]

Thanks for this, we were using the detail::tvec/tmat's wherever we had templated functions that operated on multiple value types or dimensions (like here), but this change will make it appear less hacky.

[Groovounet]

Welcome!

Note that GLM provides "areOrthogonal" function in GTX_vector_query.

[Groovounet]

'slerp' is also implemented in GTX_rotate_vector.

[richardeakin]

Our orthogonal() method is a bit different as it returns a new vec3 orthogonal to the provided argument. We'll be happy to move to the slerp() you added when upgrading to 0.9.6.