Use "nvi" parameter for ENCODE hic files

[jrobinso]

For ENCODE I’ve added a new column to the file the hic maps are loaded from, the “nvi” column, its column 9. When the “config” for loading the map is created it needs to set property “nvi” to this value. I’m speaking of this file:

https://s3.amazonaws.com/igv.org.app/encode/hic/hic.txt

This can make a dramatic difference on initial load speed of ENCODE maps.