hdf5_der

[svn-r21989] Purpose: Add SWMR capability to v1 b-tree

Description:
Adds SWMR capability to v1 b-trees, and the chunk index using v1 b-trees.  With
this implementation, flush dependencies are always on when in the cache.  This
will allow attritbutes to be used for "checkpointing" data when object header
dependencies are fixed - i.e. if a writer writes data before an attribute in
that dataset's object header, then if a reader sees the updated attribute the
written data is guaranteed to be visible, as long as that dataset's b-tree nodes
are evicted from the reader's cache.

Also adds support for compression with SWMR.

Also fixes earray implementation to not free (reuse) the file space for deleted
chunks and outdated versions of compressed chunks when doing SWMR writes.  These
should eventually be added to a timeout list.

Adds testing for these cases.

Tested: durandal