Refactored lines handling in WebGLRenderer to use the same internal machinery as meshes.

No need to stuff them in different bucket, line-specific stuff is anyway done in `renderBuffer` method.

This was prompted by starting with implementation of ParticleSystem. It would be unwieldy to handle three different buckets of objects / buffers.

src/objects/ParticleSystem.js

@@ -0,0 +1,17 @@
+/**
+ * @author alteredq / http://alteredqualia.com/
+ */
+
+THREE.ParticleSystem = function ( geometry, materials ) {
+
+	THREE.Object3D.call( this );
+
+	this.geometry = geometry;
+	this.materials = materials instanceof Array ? materials : [ materials ];
+
+	this.autoUpdateMatrix = false;
+
+};
+
+THREE.ParticleSystem.prototype = new THREE.Object3D();
+THREE.ParticleSystem.prototype.constructor = THREE.ParticleSystem;