How to deal with swizzling in glm 0.9.5+?

Related issue, https://github.com/g-truc/glm/issues/98
Swizzling macros changed, you have to use parenthesis now.
For example in camera.cpp:385
```
    -    glm::vec3 lookat = glm::row(m_view, 2).xyz;
    +    glm::vec3 lookat = glm::row(m_view, 2).xyz();
```
How to deal with that?
Two possible solutions:
- update code base to match with new macros (clean way)
- add static 0.9.4 dependency to this repository and link it as glm is a header only library this should be easy to set up (messy way)

To review the code changes I will add an example pull request to this issue.