search in dconf-editor should be wrapped around (circular, looped search)

[Norbert]

Steps to reproduce:
1. Launch dconf-editor from Ubuntu 16.04.1 LTS (dconf-editor version 3.18.2).
2. Try to Search some text
3. Click Next several times to reach last item.
4. Try to Search another text - it will not be found.

Expected behavior:
When reached last entry in the elements tree the cursor (selection) is moved to its start. So user can search text in wrap-around (circular, looped search) mode.

Actual behavior:
User is unable to find anything if the last entry is reached.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: dconf-editor 3.18.2-1
ProcVersionSignature: Ubuntu 4.4.0-34.53-generic 4.4.15
Uname: Linux 4.4.0-34-generic i686
NonfreeKernelModules: wl
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: i386
CurrentDesktop: MATE
Date: Sat Aug 20 20:54:23 2016
InstallationDate: Installed on 2016-04-21 (120 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release i386 (20160420.1)
SourcePackage: dconf-editor
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.