Bug fix: `IndexStreamBuffer` prematurely throws data-exhaustion error.
- When fewer than the requested number of bytes are read from a stream, keep reading until the stream is actually exhausted.
Fix typo in error message
Merge pull request #75 from samtools/mm_bugfix_bam_index_input_stream_api_compliance

Bug fix: `IndexStreamBuffer` prematurely throws data-exhaustion error.
Bug fix: if `this` has a field with value `null`, `equals()` throws a `NullPointerException` despite that being a valid state.
Merge pull request #77 from samtools/mm_bugfix_metrics_equals

MetricBase NPE fix