update MetaSearch to 0.3.1
remove code
merge back ef0e7d09168d43b0529a1f819108a4741c7e9e75
Visibility groups: also record visibility states of renderer categories (legend nodes) into groups

Visibility of a layer is not stored within the map layer, but visibility
of renderer categories (which turn into legend nodes) is stored inside renderer and
that one in turn inside map layer. This fact may result in surprising behavior
when change of visibility group for a composer map will affect other composer maps (and main canvas).
The only way to overcome the problem would be to have the possibility to use multiple renderers with one layer.
[FEATURE] Toolbar for layer tree specific actions
Fix #11143 (remove visibility groups after removal of a layer)
Keep a bit of spacing in layer tree dock widget
If layer is in editing mode, show the pencil icon instead of embedded legend icon
Respect the overridden layer name in composer legend also in rendered legend
Fix #11126 (Make up/down buttons work also for layer tree nodes)
Fix QgsLayerTreeModel naming conventions and update Python bindings

I was using a mixture of terms 'symbology items' and 'legend nodes' for the same thing which was confusing
Fix potential crash when adding a group
Merge pull request #1575 from geopython/MetaSearch-0.3.1

Meta search 0.3.1
Start of doxygen page about API breaks
Do not create collaboration diagrams in doxygen docs

The diagrams do not really add much value and do not highlight the important concepts
of classes, confusing the user and making things looks more complicated than they are
Fix yesterday's changes to currentGroupNode() (fixes addition of groups)
Remove some superfluous empty vertical space from browser dock widget
fix metasearch syntax error