Ability to select which taxonomies will be used to create the breadcrumbs (patch attached)

This was mentioned in another issue which I now cannot find! There was a feature request for which a patch was submitted which included this fix but this was taken out before being applied to the dev version in order that a patch contain only one fix. Since I wanted this feature I took the code from the patch, modded it slightly and made my own patch.

What does it do?
It allows you to select which taxonomies you want the breadcrumbs created for. Any unselected will be ignored. It makes a small adjustment to one of the queries so should have a negligible performance hit. If none are selected it will create the breadcrumbs for all taxonomies as before.