ADDED: Config for doxygen.
FIXED: Wrong #ifdef
Moved coordinate conversions into separate files
Merged branch 'engine' into tests: changes in the structure of the
engine.
FIXED: Compatibility with the engine.
Merge branch 'engine' into raytracer: changes in the structure of the
engine.
FIXED: Compatibility with the engine.
Provided more documentation for numeric.h
FIXED: Angular momentum setting
Documented geometry.h
More documentation: integrators, Particle, Entity and some cosmetic
changes in geometry.
More fixes in documentation in geometry.h
Merged latest changes on branch 'engine' into tests
Merged latest changes from branch 'engine' into raytracer
Merge branch 'tests': updated tests
Merge branch 'raytracer': updated the raytracer