Fix inverted polygon renderer test
Fix PalLabeling tests

Switch to QgsMultiRenderChecker and add control images for Ubuntu precise where
required.
[unit tests] Make qgis_rendererstest pass

Replace control image
Fix shapeburst test

Move to multirenderchecker
Cleanup atlas composition tests

 * Don't try to cache on 0-sized image
 * Use qDebug instead of qWarning
Use a non-transparent background for composition checker

Fix composerhtml tests on precise
Switch to RGB32 images for composition checker
RGB32 bg changes for mrc
Add QgsDartMeasurement
Disable geometry simplify check

This test mixes different effects and is very unprecise in what it tests and
what it expects as result.
Exclude PyQgsPalLabelingCanvas test because of Segfault on test server
Fix atlas test

 * Recreates composition for every test and therefore removes internal
   dependency
 * Reorders method calls to make the test pass
Fix atlas with fixed scale
Remove SymbolLayerV2Check