#2449 Massive overhaul of HDF5 writing.  Chunks can now be any shape and size.  The algorithm chooses the dimensions to be efficient and < 1 MB.  Both reader and writer (through the abstract class) get an increased cache (from default to 128 MB).

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@20456 b5f69653-2bf5-0310-8201-b0dafb8e1405
#2449 Better comment.

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@20457 b5f69653-2bf5-0310-8201-b0dafb8e1405
Mend my build Jumpfh!

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@20458 b5f69653-2bf5-0310-8201-b0dafb8e1405