[YAGGLER/3rdPARTY/GLM]: added glm into the YagGLer build system.
[YAGGLER/CMake]: cleaned up a bit the build system (and added GLM)
[YAGGLER/SAMPLES/9SLICES]: added a simple sample that perform a 9-slices on a given image
[YAGGLER/3rdPARTY/GLM]: added the glm/glm.h inclusion in yaggler.hpp