Construct 3 SpriteStack effect

This is a port to Construct 3 of the excellent shader from @Securas2010 (many thanks for the permission to share it with the C3 community.) It's a work in progress, but fun to play with. It's an alternative to using multiple sprites and Z elevation in C3. This is a collab with hcatarrunas from Construct Discord who was helped a lot with the sample project, shader edits, good settings for the shade…