[Feature Request] Looking to get support for 2nd UV channel

This is a feature that most if not all environemnt artsits in the video game indsutry including myself have been looking to get since pretty much Substance Painter came out. 
The 2nd UV channel is widely used in most games across the industry and has been for years now. Current work around that we all have been doing is to copy the UVs from the 2nd UV channel into the first and then deleting the 2nd UV channel which is cumbersome. 

Additionally with a lot of things that use trim sheets for texture information as well as a 2nd UV channel for additinal texture information Painter could benefit from getting the information mapped to the 1st UV channel and applying it to 2nd UV channel masks. 

I could go on but there'd be a ton of use for this 2nd UV channel feature.