Merge pull request #52 from kevmoo/master

and more cleanup
Add my self to AUTHORS.txt
Improve readme
Improve changelog
Fix a failing test
Add mix function like the GLSL mix function for double, Vector2, Vector3 and Vector4
Add more vector constuctor tests
My goal was to add a splat constructor, but that has a collision with the method with the same name. Remove the use of the non existing splat constructor from the readme
Add a tool to automaticly generate the vector_math_64 library out of the vector_math source.

dart tool\hop_runner.dart generate_vector_math_64
Add a scaledAdd function to all vectors that add a value after it was scaled by a factor
Add method to find the intersection point between 3 planes
Add calculateCorners method to Frustum class to retrieve the corners of a Frustum
Added splatter constructor to vector classes as suggested in #47
Generate new version of vector_math_64
Deprecate the sqrtOneHalf constant as dart:math comes with the same constant
Fix typo
Setup basic skeleton for color related functions
Add toGrayscale
Add fromRGBA
Implement hex color parsing and formatting
Add alphaBlend function
Add linear <=> gamma color space conversation
Rename method to match dart style guide