Generalizing search/get methods in Object3D

I often end up adding custom properties to my `THREE.Object3D` objects but it is hard to use my custom parameters to find objects. Right now there are two specific methods to find objects by a property. `getObjectById` and `getObjectByName`. My suggestion is to add a less specific getObjectByProperty method with as first param the `propertyName` or 'name' and second param `propertyValue` or 'value'. We are able to reuse this new method in `getObjectById` and `getObjectByName`. This ends up in less code with more flexibility.

An additional suggestion would be to add a get method to find by `uuid` like this:

`````
getObjectByUuid: function ( uuid, recursive ) {

    return this.getObjectByProperty( 'uuid', uuid, recursive );

},

`````

I hope you guys also see advantages in this change.
AudioListener: Minor clean up.
Merge branch 'patch-1' of https://github.com/Wilt/three.js into dev
Object3D: Code clean up.
Material docs todos
Implemented off-axis stereoscopic rendering
Styling, comments and unused code removal
Merge pull request #5703 from TatumCreative/docs-materials

Material docs todos
added raycasting to lines with buffered geometry
Merge pull request #5713 from m-schuetz/bg_line_support_in_raycaster

added raycasting to lines with buffered geometry
Updated builds.
Removed MatrixAutoUpdate From Aniamtion

Removed the lines forcing MatrixAutoApdate and MatrixWorldNeedsUpdate to true from Animations update and reset. Per Issue #5704
Merge pull request #5715 from titansoftime/dev

Removed matrixAutoUpdate From Animation
_this.info.memory.geometries now counting BufferGeometry correctly
Animation.js - Don't return before rendering the last frame
Merge pull request #5727 from galvanix/fix-last-animation-frame

Fix non-looped animations ending before last key is applied
Renderer docs
WebGLRenderTarget missed todos
Fixing path to Cube and CombinedCamera in source
Updating documentation for CubeCamera