Various patches

Patches to move the implementation of virtual destructors to .cpp files
rather than inline in the headers.  Some versions of GCC have issues
with not generating a vftable at all if a virtual function is not
defined in a cpp file.  This can cause dynamic casts to fail and other
sorts of havok.
Checking for srs validity in ExtrudeGeometryFilter.
Exporting osgEarth::Features::Filter
Merge branch 'topic-makpatches'
Fixed bug in EarthManipulator for touch events on iOS (needs tested for Android).
Added clamping technique to fix slow qt annotation tools.
Merge branch 'master' of github.com:gwaldron/osgearth
Added a custom bounding box option to the TFSPackager
Merge pull request #368 from flyncode/master

Added a custom bounding box option to the TFSPackager
Removing unused code in LinearLineOfSightNode.
Removed unused get/setFrame functions from Controls.
Fix clamping of radius draggers in Annotation Editors.
Removed unneeded 64BIT_BUILD CMake changes.
Change so that overlays use accumulated view matrix instead of current camera view matrix, fixing incorrect feature display when MapNode is under sub-camera.
Remove some redundant code in OverlayDecorator.cpp.
Merge pull request #372 from rolandhill/rtt-subcamera

Change so that overlays use accumulated view matrix instead of current c...
MP perf updates: moved TK unis to MPGeometry, temp disabled birth_time uni, consolidated surface and skirt drawables. Also Extrude/Build perf: added Tim optimizations for vertex cache ordering to acheive big gains
Merge branch 'master' into topic-mp-performance
Making it so the destination bounds in the TFS packager are specified in the destination SRS instead of the feature source's SRS.
Merge branch 'master' of https://github.com/gwaldron/osgearth
MPGeometry comments
Merge branch 'master' of github.com:gwaldron/osgearth
Fixed issue with 2x2 heightfields and the triangulate interpolation method

The -2 should be a -1 anyway, getting the heightfield at a pixel on the
exact upper right of a height field didn't work previously.