message: added Sphere.fromBox3D
diff: /**
  - * Copyright (c) 2018 mol* contributors, licensed under MIT, See LICENSE file for more info.
  + * Copyright (c) 2018-2019 mol* contributors, licensed under MIT, See LICENSE file for more info.
  *
  * @author David Sehnal <david.sehnal@gmail.com>
  * @author Alexander Rose <alexander.rose@weirdbyte.de>
  @@ -9,6 +9,7 @@ import { Vec3, Mat4, EPSILON } from '../../linear-algebra'
  import { PositionData } from '../common'
  import { OrderedSet } from 'mol-data/int';
  import { NumberArray } from 'mol-util/type-helpers';
  +import { Box3D } from './box3d';
  interface Sphere3D { center: Vec3, radius: number }
  @@ -76,6 +77,12 @@ namespace Sphere3D {
  return out
  }
  + export function fromBox3D(out: Sphere3D, box: Box3D) {
  + Vec3.scale(out.center, Vec3.add(out.center, box.max, box.min), 0.5)
  + out.radius = Vec3.distance(out.center, box.max)
  + return out
  + }
  +
  export function addSphere(out: Sphere3D, sphere: Sphere3D) {
  out.radius = Math.max(out.radius, Vec3.distance(out.center, sphere.center) + sphere.radius)
  return out
  