initial euler3 class.
add draft for Euler3.clamp().
complete Euler class, update examples, update Object3D, update unit tests.
added notices that Vector3.setEulerFromRotationMatrix/setEulerFromQuaternion have been removed.  Not deprecating because the target class has changed, it isn't just a function rename.
Merge branch 'dev' of git@github.com:mrdoob/three.js.git into euler3
remove self.performance.now support from header.js, it is no longer needed.
change encoding of webgl_marching_cubes.html to UTF8 so that it loads as an interactive page rather than as plain text.
add THREE.Rotation and remove Object3D.useQuaternion (as we always use quaternion now.)  Following recommendation discussed here: https://github.com/mrdoob/three.js/issues/3404#issuecomment-17262516
improve handling of unspecified orders in Euler.setFrom*() functions.  Fill out Euler.clamp().
implement initial Euler.reorder() function and remove Euler.alternativeSolution() per @WestLangley.
Added Euler unit tests, fixed one bug in Euler, one bug in Rotation.
remove Euler.clamp and Math.fpModulus per @WestLangley.
Add two color arguments to GridHelper so that the grid color is not hardcoded
Add setColors method to GridHelper, Add example for setting up and changing colors of a grid
Merge remote-tracking branch 'verma/configurable-colors-for-grid-helper' into dev
Merged grid helper example into helpers example.
Updated builds.
README: Added result link to usage section.
#fixes 3579

I haven't tested the problem but it was a bad idea anyways to have start and end have the same referenceObject
#fixes 3539

There was no need for the load texture to be static