#2031 Modified `IsSiteAvailiable` method to take a `CellPtr` for use in determining site availability.



git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18368 b5f69653-2bf5-0310-8201-b0dafb8e1405
#1660 Fix acceptance tests again.  Note APD map has no trailing tabs.

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18369 b5f69653-2bf5-0310-8201-b0dafb8e1405
git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18372 b5f69653-2bf5-0310-8201-b0dafb8e1405
#2351 Re-factor to pull of element concentration

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18374 b5f69653-2bf5-0310-8201-b0dafb8e1405