Use @gmod/tabix-js for tabix access

[rbuels]

Uses the new @gmod/tabix npm module for all tabix code.

Improves performance, and fixes the issues that have been seen with large VCF headers (@cmdcolin's large VCF header test has been enabled now and is passing)

fixes #1147, fixes #1139, fixes #1195

[cmdcolin]

Has this been tested on the data dir in #1195? I think there are some glitches that show up in gene models after applying these changes

before

after

[rbuels]

i ended up needing low-level control of unzipping in tabix-js, to stop unzipping a set of data when we come to the end of the chunk. if we unzip block by block and keep track of the block lengths during unzipping, we can unzip exactly the right amount

this actually led to a large speedup in the UI as well, which I was not expecting

@cmdcolin i think this fixed the gff3 bug you were seeing, could you look again?

[cmdcolin]

Looks like it's pretty good. The feature labels aren't being displayed on the genes though?

[cmdcolin]

Maybe that's because it's determining it's too dense to display the feature labels?

[cmdcolin]

Also sometimes the mouseover shadow does not appear on the feature you are hovering over? I'm just scrolling around that ncbi human data

[cmdcolin]

At this zoom level NCF2 is not mouseoverable but zooming in it seems able to be mouseovered just fine NC_000001.11:183538351..183601700 (63.35 Kb)

[rbuels]

@cmdcolin set topLevelFeaturesPercent = 10 on the track conf and see if that makes it behave more as you expect. added that config switch so people can fix the indexedstats line count-based stats. it counts a whole bunch of lines, but they pretty much collapse into only about 10% as many top-level features

[cmdcolin]

This is looking very good. The topLevelFeaturesPercent seems like a reasonable correction factor for stats estimation. The mouseover issue I mentioned above could have been a fluke, I think things are looking good now!