Fixed rule of 3 violations in many places.

* Added virtual qualifier to a few destructors in subclasses.
* Removed a few empty destructors that didn't need to be explicitly defined.
* Fixed a few typos
* Removed unnecessary empty virtual destructors in some classes with parent's who derrived from a class with a virtual destructor

RecastDemo/Source/SampleInterfaces.cpp

@@ -23,10 +23,6 @@ BuildContext::BuildContext() :
 	resetTimers();
 }
 
-BuildContext::~BuildContext()
-{
-}
-
 // Virtual functions for custom implementations.
 void BuildContext::doResetLog()
 {