expand Matrix3 with set, identity, copy, multiplyScalar, deteminant, clone;  Matrix3/4.getInverse will now optionally throw an exception; start Matrix3/4 unit tests

if and return series suggested by mrdoob here: https://github.com/bhouston/three.js/commit/6c765dcdb2c790ddcc5d613e96be8a0e66eca1f8#commitcomment-2346419

add Array storage as another alternative to the Vector3 storage benchmark.  fix bug in Float32Array length method.

use switch statements in Vector2/3/4.getComponents()/setComponents() based on it being 5-10x faster than index-to-name based on benchmark_vector3components.html

inline Vector2/3/4/Quaternion.length()/lengthSq() and optimize Vector2/3/4.setLength() with unit test coverage.

remove duplicate Quaternion.toEuler (already on Vector3.setEulerFromQuaternion), expand Quat unit test, fix merge.

Conflicts:
	test/sources.html

add new credits to Quaternion.js, expand Quaternion unit tests, move Matrix4 set* methods to standard file location.

Also more shader refactoring and unifications across light types.