Running DepthyViewer on PIXI 4

[gorelics]

Hi there, I changed some stuff from DepthyViewer class to make working with PIXI 4, but DepthPerspectiveFilter works unexpected, DepthDislacementFilter works as expected

Extracted and fixed depthy files here https://codepen.io/gorelics/project/editor/AdzvKm

[gorelics]

All works as expected))) We can use DepthyViewer as standalone lib, but some export functions need to be fixed too to latest PIXI APIs