add Vector3.project, Vector3.ortho and Vector3.reflect based on request by #3009
move build related files in /utils to /utils/build
update examples.json to new location in utils/build subdirectory
optimize Vector3.reflect, unit tests still pass.
simplify extend because we don't need it to be hierarchical.
simplify variable naming in THREE.extend, now referencing _.extend as the template.
add EMCASCript5 compatibility to THREE.extend.

Signed-off-by: Ben Houston <ben@exocortex.com>
rename cosTheta variable in Vector3.project per @WestLangley
Vector3: project->projectOn, ortho->orthoTo per @WestLangley
Vector3.projectOn/reflect: normal arg to unitNormal.  Removed Vector3.orthoTo
Vector3.projectOn -> projectOnUnit, added projectOnVector.
remove Vector3.projectOnUnit, add Vector3.projectOnPlane (equivalent to previously removed orthoTo).
THREE.extend improvements: adopt safe {}.hasOwnProperty method source.  Optimize Object.keys() based on @paulmillr suggestion.
upupdate node module building code to support new location of utils/build scripts.
Merge remote-tracking branch 'bhouston/utils-build-move' into dev
Merge remote-tracking branch 'bhouston/reflect-ortho-project' into dev