A class representing [link:http://en.wikipedia.org/wiki/Euler_angles Euler Angles].
			Euler angles describe a rotational transformation by rotating an object on its various
			axes in specified amounts per axis, and a specified axis order.
		
Iterating through a [name] instance will yield its components (x, y, z, order) in the corresponding order.
const a = new THREE.Euler( 0, 1, 1.57, 'XYZ' );
		const b = new THREE.Vector3( 1, 0, 1 );
		b.applyEuler(a);
		
		
		[page:Float x] - (optional) the angle of the x axis in radians. Default is `0`.
		[page:Float y] - (optional) the angle of the y axis in radians. Default is `0`.
		[page:Float z] - (optional) the angle of the z axis in radians. Default is `0`.
		[page:String order] - (optional) a string representing the order that the rotations are applied,
		defaults to 'XYZ' (must be upper case).
		
Read-only flag to check if a given object is of type [name].
			The order in which to apply rotations. Default is 'XYZ', which means that the object will first be
			rotated around its X axis, then its Y axis and finally its Z axis. Other possibilities are:
			'YZX', 'ZXY', 'XZY', 'YXZ' and 'ZYX'. These must be in upper case.
			Three.js uses `intrinsic` Tait-Bryan angles. This means that rotations are performed with respect
			to the `local` coordinate system. That is, for order 'XYZ', the rotation is first around the local-X
			axis (which is the same as the world-X axis), then around local-Y (which may now be different from the
			world Y-axis), then local-Z (which may be different from the world Z-axis).
		
			The current value of the x component.
		
			The current value of the y component.
		
			The current value of the z component.
		
Copies value of [page:Euler euler] to this euler.
Returns a new Euler with the same parameters as this one.
Checks for strict equality of this euler and [page:Euler euler].
		[page:Array array] of length 3 or 4. The optional 4th argument corresponds to the [page:.order order].
		Assigns this euler's [page:.x x] angle to `array[0]`. 
		Assigns this euler's [page:.y y] angle to `array[1]`. 
		Assigns this euler's [page:.z z] angle to `array[2]`. 
		Optionally assigns this euler's [page:.order order] to `array[3]`.
		
		Resets the euler angle with a new order by creating a quaternion from this euler angle
		and then setting this euler angle with the quaternion and the new order. 
		*Warning*: this discards revolution information.
		
			[page:.x x] - the angle of the x axis in radians.
			[page:.y y] - the angle of the y axis in radians.
			[page:.z z] - the angle of the z axis in radians.
			[page:.order order] - (optional) a string representing the order that the rotations are applied.
			Sets the angles of this euler transform and optionally the [page:.order order].
		
		[page:Matrix4 m] - a [page:Matrix4] of which the upper 3x3 of matrix is a pure
		[link:https://en.wikipedia.org/wiki/Rotation_matrix rotation matrix] (i.e. unscaled).
		[page:.order order] - (optional) a string representing the order that the rotations are applied.
		Sets the angles of this euler transform from a pure rotation matrix based on the orientation
		specified by order.
		
		[page:Quaternion q] - a normalized quaternion.
		[page:.order order] - (optional) a string representing the order that the rotations are applied.
		Sets the angles of this euler transform from a normalized quaternion based on the orientation
		specified by [page:.order order].
		
		[page:Vector3 vector] - [page:Vector3].
		[page:.order order] - (optional) a string representing the order that the rotations are applied.
		Set the [page:.x x], [page:.y y] and [page:.z z], and optionally update the [page:.order order].
		
		[page:Array array] - (optional) array to store the euler in.
		[page:Integer offset] (optional) offset in the array.
		Returns an array of the form [[page:.x x], [page:.y y], [page:.z z], [page:.order order ]].
		
[link:https://github.com/mrdoob/three.js/blob/master/src/[path].js src/[path].js]