Update to SFML 2.0.

Added todo-file to version control.

Configure script now works when build is a symbolic link

Documentation about explicit procedural algorithms

Rationale for helsing square

Explicitly allowed copy/assignment construction of classes that support it.

Copy and assignment constructor in MatrixStack

Disabled the default copy constructor for some classes.

Made all constructors explicit.

Additional documentation in Continuous2DSignal

Specular lighting in phong shader

Redused specular component a tiny bit

Specular lighting for goraud shader

Phong shading had didn't check for negative diffuse shading

Fixed small bug that occured due to rounding errors