Merge pull request #28 from johnmccutchan/master

s/num/double
Updated documentation
Add addBody interface to world. Allow for custom Body subclasses.

Issue #8
Update to latest SDK: r30798
Add testPoint to Fixture
Add raycasting support. Fixes issue #29
Use vector_math for transform operations.

Fixes issue #20.
Merge branch 'master' of https://github.com/dart-lang/dart-box2d

Conflicts:
	example/benchmarks/benchmark_runner.dart
	lib/box2d.dart
	lib/src/collision/broadphase/dynamic_tree.dart