Merge remote branch 'upstream/master'
Add normal computation for polygons
Morphing experiments
fixed MapNode.cpp to ensure that a handle to osgEarth::TerrainEngineNode is held, particularly during initialization of the map node.  Exception can occur without this change when loading the osgearth scene graph from a thread, as update/render occurs in the main thread.

The culprit is in osgViewer/Viewer.cpp here...
    // update the Registry object cache.
    osgDB::Registry::instance()->updateTimeStampOfObjectsInCacheWithExternalReferences(*getFrameStamp());
    osgDB::Registry::instance()->removeExpiredObjectsInCache(*getFrameStamp());

... removeExpiredObjectsInCache() deletes the TerrainEngineNode and causes the exception.
Merge pull request #289 from poweroftwo/EnsureMapNodeKeepsTerrainEngineRef

fixed MapNode.cpp to ensure that a handle to osgEarth::TerrainEngineNode...
Added the TimeControl interface, and updated the WMS driver to support it; finally, added a new "osgearth_sequencecontrol" example to show how to use the interface.
Fix gcc compile issue in ReaderWriterWMS
Added the new "mp" terrain engine driver. First draft.
MP: break MPGeometry out into its own file; other cleanup.
BUG: fixed the broken texcompositor (draping/clamping bust)
Added DataScanner; added --images option to osgearth_viewer to search for and load image layers.
Search QT4 only when it is needed

When one build osgEarth with a iOS CMake Toolchain file, then it should not find a MacOSX QT package. This generates warnings on CMake.
QT should only be searched when it needed.
Merge pull request #290 from remoe/patch-1

Search QT4 only when it is needed
Added osgearth_viewer --images option to load all imagelayers form a folder.
Static initialization cleanup work.
MP: add default texture
Merge branch 'master' of github.com:gwaldron/osgearth
MP: consolidate terrain root key code
MP: proper blending support for shaders; proper texture precompilation
ImageUtils: add alpha region color-matching so we don't get blending errors in MP