Make WMS server use QgsLegendRenderer
Fixed bugs with feature count, maintenance of QgsLegendSymbolItemV2
Use QgsLayerTreeModel as a source of data for legend rendering instead of QgsLegendModel

This is work in progress, customization of legend is not working yet
Moved QgsLayerTreeModelLegendNode (+derived classes) to a new file
Support for custom labels in symbol-v2 legend node
New flag to disable checkboxes for legend nodes in layer tree model
Layer tree model support replacement of layer tree + layer node handles removal of layer cleanly
Work in progress: Make composer legend widget work with QgsLayerTreeModel
Legend customization via layer node's custom properties

This allows for reordering, renaming and removal of legend nodes.
Composer either uses default project layer tree (auto-update on)
or customized layer tree (auto-update off).
Fix WMS with custom rule / no labels
Introduce scale-based filtering of legend nodes (in WMS)
Improve docs for QgsLegendSymbolItemV2
Update Python bindings
API fixes, added missing python wrappers
Revert previous changes to QgsLegendModel and its items
More Python wrapper updates + fixes
Added header to new files
Fix #11006 (wrong size of symbols in print composer legend if map units are used)
Followup fix for #11006 (spotted by Nyall - thanks)
Fix doxygen warnings, fix missing bindings