hdf5doc

Description:
    Added links to external links functions.
    Moved the most-recently completed work from the end to the 
        beginning of the list.
    Moved SOHM functionality to the "in this release" section.
        (There are performance and storage space enhacements still 
        due, but the basic functionality will be unchanged.)
    Added "API compatibility macros" to "Remaining Anticipated Changes..." 
    Added "'Use the Latest Format' Enhancements" bullet to final section.
    Added h5copy to "Tool Improvements" and "Object Copying" discussion.
    Several smaller revisions, copy edits, etc.
Tested:
    Firefox