[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/H5DataSet.cpp

@@ -199,7 +199,7 @@ void DataSet::p_close() const
 // a member function so it can be template to work around that problem.
 DataSet::~DataSet()
 {
-   // The dataset id will be closed properly
+   // The dataset id will be closed properly 
    resetIdComponent( this );
 }