Use a QDoubleSpinBox instead of a QLineEdit for the snapping
 tolerance, make the treeview columns adjust better to the size of the
 contents
Use GEOS reentrant API (_r functions) and update requirement to GEOS >= 3.1.0

Currently QGIS uses the 'classic' GEOS API that uses a global context.
This can conflict with libraries that would also use the global context
and potentially finalize it whereas QGIS will still use it later.

See https://groups.google.com/forum/#!topic/spatialite-users/9YSU6c5AVQ4 for
such an example of such a recent issue with Spatialite.

The _r API is available since GEOS 3.1.0, which is already an ancient GEOS
version. For example, old-old-stable Ubuntu (Lucid 10.04) and Debian (squeeze)
ship with GEOS 3.1.0 or later.

Such move has also been done in GDAL 1.11
(http://lists.osgeo.org/pipermail/gdal-dev/2013-August/036877.html)
and MapServer 7.0 (https://github.com/mapserver/mapserver/issues/4733)

There's no easy way unfortunately to check at compile time that you don't
use the non _r API. I have patched my geos_c.h header to #ifdef that API (quite
painfull to do..). A postprocessing check can be done however with :

objdump -T output/lib/*.so | grep -v Base | grep GEOS | grep -v _r | grep -v "_ZN" | grep -v GEOSversion

It should return nothing.
fix doxygen warnings
Fix GEOS dev detection (fixes #11081)
grass provider: catch unavailable mapserver (fixes #11025)
Fix #11092:
* fix crash when invalid shapefile layer is repacked
* error out if vector file writer is invoke with an empty filename
* don't allow "Save as..." without a given filename
Allow removing last point while measuring via del/backspace keys (fix #10176)
Merge pull request #1569 from nyalldawson/measure_undo

Allow removing last point while measuring
german translation update
debian packaging update
Move bits of legend rendering code into item classes + add rendering test
Automatic creation of composer legend symbol item icon
Creation of legend items for map layers moved to QgsMapLayerLegend
Scale range supported by symbol in QgsLegendSymbolItemV2
Identify renderer's categories/rules by key instead of index
Added support for check states to rule-based renderer
Fix crash in WMS GetLegendGraphics
Fix rendering of WMS Legend Graphics
Fix nested WMS layer data items
Force vector output for preview icon so it avoids cached pixmaps