deactivate qgis_wcsprovidertest

Disabling on behalf of @m-kuhn since the wcs server used in qgis_wcsprovidertest is not really reliable. Often the test fails due to server problem.
We should use a more solid server or make the test handle connections problems
Make the "Merge shapefiles" tool correctly handle features without geometries.
[processing] fixed help in models
Merge pull request #1697 from mbernasocchi/patch-1

deactivate qgis_wcsprovidertest on travis

It depends on an unreliable external service and therefore produces false alarms.
add a save button for subform (1-n relations)
clean code style with prepare-commit.sh
remove repaint when layer is not modified
Fix crash on exit: Close all cached sqlite connections
Remove help button from symbollevelv2 dialog

There is no help text available for this dialog and the button does nothing at
all at the moment
Fix #10727 - Add update selected button to field calc bar
Add toolbar icon and shortcut for python console
Fix potential crash in random color ramp

Badly choosen values (eg max < min) could cause a crash. Now, values
are sanitised prior to generating the ramp colors.
Fix grammar
[FEATURE] Support drag and drop of python scripts onto QGIS window
Fix incorrect warning dialog appearing when creating new ramp

Previously a "not available" warning dialog would appear when
attempting to create a new color ramp using the categorised renderer.
[symbology] Add method for retrieving symbol layers as list
Streamline singleton behavior in a class QgsSingleton

If a singleton is unused in an application, it's not going to be created just
to be deleted instantanously on app exit.
QgsCoordinateTransformCache will also be cleaned on exit.
Revert "Streamline singleton behavior in a class QgsSingleton"

This reverts commit e1f6edbd55122e6d2206daf4a0b55e3e9207cf80 as it breaks tests
Streamline singleton behavior in a class QgsSingleton, take two

delete provider registry after map layer registry to avoid crashes
INSTALL: update required flex version to 2.5.6 and links to windows version