To store the CRAM interleave and demultiplex codecs.

I am unsure at present if these are necessary and will make the v3.0
official release.


git-svn-id: svn://svn.code.sf.net/p/staden/code/io_lib@3684 ba6f2710-ca9f-427c-89d3-5bf716dbc8e1
Interleave codec implemented and place-holder for demultiplex.


git-svn-id: svn://svn.code.sf.net/p/staden/code/io_lib@3685 ba6f2710-ca9f-427c-89d3-5bf716dbc8e1
Put BD:Z and BI:Z into separate external blocks instead of merging
together as on the files I've tested it seems to work better. Is this
normal? I wonder what file I looked at that initially lead me to
believe the opposite now.


git-svn-id: svn://svn.code.sf.net/p/staden/code/io_lib@3686 ba6f2710-ca9f-427c-89d3-5bf716dbc8e1