updated layers doc to remove reference to masks

docs/api/core/Layers.html

@@ -11,15 +11,15 @@
 		<h1>[name]</h1>
 
 		<div class="desc">
-		An object providing a [link:https://en.wikipedia.org/wiki/Mask_(computing) bit mask] and accessor methods
-		used to control an [page:Object3D]'s visibility.
-		A [page:Layers] object assigns an [page:Object3D] to 0 or more of 32 layers numbered 0 to 31.<br /><br />
+      A [page:Layers] object assigns an [page:Object3D] to 1 or more of 32 layers numbered 0 to 31
+      - internally the layers are stored as a [link:https://en.wikipedia.org/wiki/Mask_(computing) bit mask], and by default all
+      Object3Ds are a member of layer 0.<br /><br />
 
-		This is used to control visibility - an object must share a layer with a [page:Camera camera]
-		to be visible when that camera's view is renderered.<br /><br />
+       This can be used to control visibility - an object must share a layer with a [page:Camera camera] to be visible when that camera's
+      view is renderered.<br /><br />
+
+      All classes that inherit from [page:Object3D] have an [page:Object3D.layers] property which is an instance of this class.<br /><br />
 
-		All classes that inherit from [page:Object3D] have a [property:layers] property which is an instance
-		of this class.
 		</div>
 
 
@@ -28,14 +28,14 @@
 
 		<h3>[name]()</h3>
 		<div>
-		Create a new Layers object, with an initial mask set to 1 (layer 0).
+		Create a new Layers object, with membership initially set to layer 0.
 		</div>
 
 		<h2>Properties</h2>
 
 		<h3>[property:Integer mask]</h3>
 		<div>
-		Internal layer mask.
+		  A bit mask storing which of the 32 layers this layers object is currently a member of.
 		</div>
 
 
@@ -45,35 +45,35 @@
 		<div>
 		layer - an integer from 0 to 31.<br /><br />
 
-		Remove *layer* from the mask.
+		Remove membership of this *layer*.
 		</div>
 
 		<h3>[method:null enable]( [page:Integer layer] )</h3>
 		<div>
 		layer - an integer from 0 to 31.<br /><br />
 
-		Add *layer* to the mask.
+		Add membership of this *layer*.
 		</div>
 
 		<h3>[method:null set]( [page:Integer layer] )</h3>
 		<div>
 		layer - an integer from 0 to 31.<br /><br />
 
-		Set the layer mask to the value *layer*.
+		Set membership to *layer*, and remove membership all other layers.
 		</div>
 
 		<h3>[method:Boolean test]( [page:Integer layers] )</h3>
 		<div>
-		layers - a 32bit bit mask of layer numbers.<br /><br />
+		layers - a Layers object<br /><br />
 
-		Returns true if *layers* and [page:.mask] have any bits set in common.
+		Returns true if this and the passed *layers* object are members of the same set of layers.
 		</div>
 
 		<h3>[method:null toggle]( [page:Integer layer] )</h3>
 		<div>
 		layer - an integer from 0 to 31.<br /><br />
 
-		Toggle the *layer* value in the mask.
+		Toggle membership of *layer*.
 		</div>
 
 		<h2>Source</h2>