Added 3D display object properties to tweener
Specialized 2D matrix calculations in Matrix3D

A little less work for the CPU
Add documentation for sprite
Add more documentation to display classes
Use the triple slash /// comments according to the Dart Style Guide
Merge pull request #158 from marcojakob/display-documentation

More display classes documentation
Update getting_started.md
Added ChromaKeyFilter

Kudos to @sebgeelen for the implementation.
Added Video implementation

Kudos to @sebgeelen for the initial implementation which was slightly
changed by me.
Update AUTHORS.md

Added Sébastien to the authors
Update AUTHORS.md
Fixed render loop
Changed name of constructor

It is very unlikely that someone used this constructor, so it's a minor
breaking change.