Add ability to remove subgrains which are not touching another class

[tcatley]

Add ability to remove subgrains which are not touching another class (i.e. remove protein subgrains in a crop which do not touch the DNA subgrain)

Example images -

The protein to the top left of the DNA would ideally not be included (or given a different class) as it is not touching the DNA.

[SylviaWhittle]

This will be easy to add into the vetting steps. Simple case of iterating over class B and checking if each instance touches class A and if not, deleting.

[llwiggins]

We may not want to delete though, for example if we want to compare statistics of unbound vs. bound!