Clarify BGZF block size: kibibytes, not kibibits; "and" is clearer (PR #839)

Author: kloetzl

SAMv1.tex

@@ -921,7 +921,7 @@ \subsection{The BGZF compression format}
 bug.}
 
 A BGZF file is a series of concatenated BGZF blocks, each no larger
-than~64Kb before or after compression. Each BGZF block
+than 64\,KiB both before and after compression. Each BGZF block
 is itself a spec-compliant gzip archive which contains an ``extra field''
 in the format described in RFC1952. The gzip file format allows the
 inclusion of application-specific extra fields and these are ignored by