[svn-r3199]

Purpose: bug fix

Description:
	I found a couple of places where virtual destructors were missing
	and could cause small memory leaks.  Also, some destructors were
	not virtual when they should be.

Solution:
	- added virtual destructors, which also free dynamically allocated
	  memory
	- added virtual to several destructors
	- also, fixed several typos

Platforms tested:
	Solaris 2.7 (arabica)

c++/src/H5AbstractDs.cpp

@@ -127,6 +127,9 @@ void AbstractDs::getDataType( StrType& strtype ) const
 }
 end of old style of getDataType */
 
+// Default destructor
+AbstractDs::~AbstractDs() {}
+
 #ifndef H5_NO_NAMESPACE
 } // end namespace
 #endif