hdf5doc

Made changes to bring this page up to 1.8.5. These changes include the 
following: 
- Added and removed some H5P and H5D functions. 
- Added links to the “API Compatibility Macros in HDF5” chapter in the RM.
- Added F90 functions where only C functions had been mentioned in the past.
- Edited sections that mentioned H5Dextend: the new function H5Dset_extent 
behaves differently.
- Removed the “3.5 Other Operations” section.
- Added captions and titles to tables, figures, examples, and function 
listings.