refactoring a couple of functions in Vec2D

Signed-off-by: Marcel Schwittlick <marzzzel@gmail.com>
implementing streap << operator overloading for Vec3D

Signed-off-by: Marcel Schwittlick <marzzzel@gmail.com>
overloading stream << operator for DoubleRange

Signed-off-by: Marcel Schwittlick <marzzzel@gmail.com>
finishes Test for Vec2D

Signed-off-by: Marcel Schwittlick <marzzzel@gmail.com>
removes toString test

Signed-off-by: Marcel Schwittlick <marzzzel@gmail.com>
refactoring Vec2D class

Signed-off-by: Marcel Schwittlick <marzzzel@gmail.com>