#2358 in Ca Models the position of a dividing cell is determined by randomly selecting from the free sites. THere is also a GetPropensity method which can be overridden in subclasses to implement directed division.



git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18388 b5f69653-2bf5-0310-8201-b0dafb8e1405
#1660 use refs for these args

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18389 b5f69653-2bf5-0310-8201-b0dafb8e1405