kin with unindexed bcf/vcf files

[Ahhgust]

Hi!
In truth this isn't a bug report but it is instead a feature request (it's a small lift however).
It'd be very nice if we could estimate the kinship coefficient on a stream-- eg, we're using some whole genome simulators and it's much more convenient to keep a summary statistic than a bazillion whole genome simulations that need to be created, indexed, summarized and then deleted.

Setting line 420 in kin.cpp to:

sr->require_index = 0;

Appears to do the trick.
Much thanks.
-August