GCC 4.4: Fixed sign conversion warnings in poly-reader.
normal_vector(): Added implementation for 1d for consistency.
Algorithms: Removed empty intersect.hpp
Removed left-over include of interval.hpp

We need tests for each functionality, otherwise such things are not caught by our tests.
affine_transform(): translation is now considered correctly.

The translation vector was overwritten by zero before rotation,
hence resulting in the mesh to be only rotated, not translated.
determinant(): Added overload for (degenerate) 1d-case.
normal_vector(): Added implementation for quadrilaterals.
Manual, Doxygen: Polished documentation.

Almost all new algorithms are documented.
Still missing: Changelog, IO, seed point segmenting