Doxygen

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@20046 b5f69653-2bf5-0310-8201-b0dafb8e1405
Add users.txt
extra doxygen
Merge branch 'master' of github.com:Chaste/Chaste

Conflicts: ode/src/common/AbstractCvodeSystem.hpp