Remove convenience cursor types from reference documentation
Remove convenience cursor types from reference documentation

Those types bloat the documentation for no real value: DropFirstCursor, DropWhileCursor, EnumeratedCursor, FilterCursor, FlattenCursor, MapCursor, PrefixCursor, PrefixWhileCursor

groue/GRDB.swift,groue/GRDB.swift,groue/GRDB.swift,groue/GRDB.swift