Remove slivar filters for sex chromosome variants

[williamrowell]

segregating_dominant_x was redundant with segregating_dominant

The more general function checks the chromosome before applying the more specific function. slivar-functions.js

Also, expression was checking for chrX, so these would have failed for hs37d5.

Related to #127

[williamrowell]

~I need to add denovo and x_denovo now.~

I remember the logic here now. We're using the more general --family-expr instead of --trio so we're not doing anything special to find de novo variants with slivar.