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.
[heatmap-plugin] replace messagebar to messagebox
[context-help] set heading to 3 for heatmap plugin and python console help file
Automatic update of label and neighboring ranges boundaries
Merge remote-tracking branch 'rouault/use_geos_reentrant_api'

Conflicts:
	src/core/pal/layer.cpp
	src/core/qgsgeometry.cpp
	src/core/qgspallabeling.cpp
Merge pull request #1570 from slarosa/heatmap-plugin

[heatmap-plugin] replace messagebar to messagebox
Merge pull request #1576 from leyan/graduatedRenderer

Automatic update of label and neighboring ranges boundaries in graduated renderer. Fix #9312. Fix #9900, Fix #10203
Merge pull request #1571 from slarosa/context-help

[context-help] set heading to 3 for heatmap plugin and python console help file
Merge pull request #1304 from manisandro/replace_lineedit_with_combobox_snappingdialog

Use a spinbox instead of a lineedit for the snapping tolerance
Move identify toolbar to top to match other docks with toolbars
Use _r GEOS API in geometry import test
GEOS context accessor for PAL
Real name of @leyan instead of pseudonym
Merge remote-tracking branch 'origin/master'
Fix #11200 (Symbology changes of a layer aren't reflected in overview panel)
Use QPlainTextEdit for message log. Less memory and much much faster then QTableWidget
Keep log button in status bar.

Removing UI elements under the user isn't good UX
Set auto raise for identify toolbar icons
Remove unused variable