Add a collectionMinMatch configuration

[qgau]

Similar to catalogMinMatch, but for collection, as the catalogMinMatch does not work for collections (tested). As catalogs are not collections (either for the DB than from the outside world), it seems fair to have a dedicated option.

[jjrom]

Since a collection is also a catalog, it would make more sense to keep only one option i.e. catalogMinMatch and apply it to the collections (this is not the case right now). Do you agree on that ?

[jjrom]

Added a specific collectionMinMatch option has we probably prefer to distinguish between catalog and collection (even if a collection is a catalog)