New upload options

I have extended the custom track file upload options with support for new files:
1. BigBed files are now supported via upload and URL. Both region and coverage tracks are generated.
2. Archives (ZIP or TAR) of two or more BigWig files are supported, resulting in a BigWigSet with each file set up as a subtrack selected by display name.
3. USeq archives are automatically converted to BigWig or BigBed tracks depending on context if support is enabled.

Additionally, uploaded Bam files are no longer sorted automatically but only when the Bam sort flag header is not set to coordinate.