Added a Logger to Sigma, that can outputs to std::cout or any other output stream. Also there a little addition in CMakeFileLists.txt to allow to generate a executable for each one .cpp file in src/tests/
Fix typo
Add FindGLM module and added the respecting FIND_PACKAGE to CMakeLists
Fixed the latest GLM breaking things

The latest GLM removes some implicit casting to glm::vec3 so it is now explicitly done.
Also glm::mul() is no longer available so changed line 666 in OpenGLSystem to use the * operator instead.

Also added a missing include to <iostream> in GLCubeSpehre.
Merge pull request #139 from Meisaka/develop

CEF in travis
Merge pull request #136 from Zardoz89/log

Added a Logger to Sigma, that can outputs to std::cout or any other ...