[previews] Track titles aren't escaped

Bug Description

Tracks with '&' in the titles cause an error with unity:

WARN 2012年08月20日 14:56:22 unity.pango <unknown>:0 pango_layout_set_markup_with_accel: Error on line 1: Entity did not end with a semicolon; most likely you used an ampersand character without intending to start an entity - escape ampersand as &amp;

I think it's safer if unity escapes the string and doesn't except the lenses to do it. (this basically applies to all preview fields except description which should allow markup).

Update: Unity 6.4 is revision 2632, so this is actually fix committed for Unity 6.6.

This bug was fixed in the package unity - 6.6.0-0ubuntu1

---------------
unity (6.6.0-0ubuntu1) quantal-proposed; urgency=low

* New upstream release.
- Fixes non-escaped character sequences in dash previews (LP: #1039020)
- Updated background layer for preview cover-art and details panels
to be 10% low-light
- Expand a PlacesGroup if it is the only category that contains results
(LP: #950710)
- Update unity autopilot tests to match autopilot API
- Updated the convert files to fix some typos in the key names
- Add gmodule dependency
- Activate proper result if the categories aren't displayed in-order
(LP: #1040101)
- Refactor device launcher icons (LP: #713423)
- LauncherController: make the controller enable the launcher struts,
based on hide-mode option (LP: #1044005)
- Launcher: make always possible to drag an icon to the bottom or top
of its sub list (LP: #1043968)
- Don't desat bfb/hud icon in DNDReset (LP: #1043963)
- Progressively adjust the speed of the minimize animation. First
time it is used is slower, then speeds up the more it is used.
(LP: #1017510)
- Implement new ordering of categories for home lens. (LP: #1043915)
- UnityWindow now implements ScaleWindowInterface (LP: #876017)
- Launcher: restore an icon position after that the dragging has been
cancelled (LP: #955561)
- LauncherDragWindow: cancel drag on window mapped/unmapped
(LP: #1044723)
- Now there is a check of an override color in RefreshColor (which is
called when a PropertyNotify event happens). Also added a check in
FullySaturateColor to a void division by zero. (LP: #975350)
- Queue redraw after cover-art texture is updated from a url/file source.
(LP: #1043947)
- Fixed ability to delete glib::Source wrapper during its callback
(LP: #1044823)
- Close preview when dash is hidden. (LP: #1045298)
- LauncherModel: rewrite the Reordering functions to keep the icon
priority deltas (LP: #761155)
- Make sure we can pass extra hints when activating preview actions.
(LP: #1046352)
- UnityWindow: scale window code improved (LP: #1033935)
- The mouse will now cause the HUD buttons to change selection
(LP: #1042692)
- "Alt+Space" shortcut to reveal the window menu is not hardcoded, but a
Compiz key option. " (Hold)" should also be translated. Made all
Compiz plug-in names and all Compiz plug-in option names in
unityshell.cpp static constants.
- remove unity --reset, it's not anymore really needed now that we are
in stable days of unity and we moved to gsettings
- Removed the variables 'oldPrev' and 'oldNext' which got assigned the
value NULL, but then were never used
- Fixed the size of the previews to 770x380 pixels. (LP: #1045243)
- UnityWindow: use smart pointers, use static close_icon (with dynamic
state) and PanelStyle context (LP: #1033935) (LP: #1045127)
(LP: #1046124) (LP: #1046126)
- Remove everything in the #ifndef USE_MODERN_COMPIZ_GL ifdefs and remove
the ifdefs alltogether. unity now requires compiz...