Added regidx API which should replace bcf_sr_regions at some point
Clean after regidx init failure; fixed build dependencies
Fix in bcf regions which in some situations would skip first

the first position on new chromosome in the loci list.
regidx: simple file format autodetection
add new test-regidx binary to .gitignore
Merge pull request #136 from mcshane/feature/ignore_test-regidx

add new test-regidx binary to .gitignore
Return type of bgzf_getc is int, not char
regidx: use size_t, not ssize_t