Merge pull request #4 from Nihlus/fix-division-rounding

Fixed rounding error in division operations.

diff --cc src/OpenTK/Math/Vector2.cs
Simple merge

diff --cc src/OpenTK/Math/Vector2d.cs
Simple merge

diff --cc src/OpenTK/Math/Vector3.cs
Simple merge

diff --cc src/OpenTK/Math/Vector3d.cs
Simple merge

diff --cc src/OpenTK/Math/Vector4.cs
Simple merge

diff --cc src/OpenTK/Math/Vector4d.cs
Simple merge