created hdf5 backend - seems to be working. Probably could use some
performance tweaking.
refactored hdf5 back by splitting large code into smaller functions.
rewrote hdf5 backend to use C API. Made Sqlite destructor virtual
added custom backend specification to App.cp via output file extension
added hdf5back test
adds better doc comment to hdf5back class. Uncomments the db file deleting
line.
changed hdf5 ext to .h5. Hdf5Back constructor takes std::string
fixed null-padding on strings issue. changed set to group so Anthony is happy.
Merge branch 'develop' of github.com:cyclus/cyclus into develop