EMI: Implement head tracking.
EMI: Implement head limits.
EMI: Fixed Actor::getWorldPosition calculating the world transform incorrectly for attached actors.
EMI: Continuously update the look at vector when looking at an actor.
GRAPHICS: Make the Shader class properly free its resources
MYST3: Properly free the OpenGL resources in the shaders renderer
OPENGL/SDL: add more debug info about OpenGL driver
GRIM: Don't put OpenGL vendor/driver name in window title. Now it wrote in debug console.
MYST3: added info in window title about Renderer
MYST3: revert info about renderer in window title and put instead into console output
MYST3: Silence a compiler warning
OPENGL/Shaders: added debug info about GLEW version
CONFIGURE: do not display "shaders disabled" in case disabled opengl
EMI: SHADERS: Rename light structure to Light

Fixes issues with some shader compilers
Merge pull request #947 from Akz-/emi-head-rebase2

EMI: Implement head tracking
GRIM: Set shadow userdata to nullptr when done with it.
GRIM: Implement a dim shader
GRIM: Implement GfxOpenGLS::dimRegion
Merge pull request #957 from klusark/dim

GRIM: Implement a dim shader
GRIM: Fix the dim shader compilation on android