This class is used by other classes to filter the set of database objects used
in diff-type operations including the diff command and the generateChangeLog
There are two basic types of filter - FilterType.INCLUDE and FilterType.EXCLUDE.
In Each filter type, a filter string can be supplied. That string is a
comma-separated list of subfilters. Each subfilter can either be a regular expression,
or a Database object type followed by a colon and then a regular expression.