hdf5_chunking_query_bmr

[svn-r19146] Purpose: Fix bug in direct IO driver

Description:

In certain circumstances, the direct I/O driver did not perform correctly when
data was unaligned.  The driver has been patched to fix this.  Also added some
potential performance improvements for the unaligned case, and strengthened the
test for whether the data needs to be aligned.

Tested: cobalt