Allow style for <stop> elements in the whitelist.  Allow gradients to refer to each other in the whitelist.  Update removeUnusedGrads() to account for this.
Allow style for <stop> elements in the whitelist.  Allow gradients to refer to each other in the whitelist.  Update removeUnusedGrads() to account for this.

ryanramage/svg-editor,ryanramage/svg-editor,ryanramage/svg-editor,trentmillar/ddp-level-editor,trentmillar/ddp-level-editor,trentmillar/ddp-level-editor