Added osg::MemoryManger which is currently based on Paul Nettle's memory manager

published at flipcode.  I havn't adopted Paul's macro's for new/delete etc, but use
osg prefixed versions instead to allow greater flexiblity in handling include
ordering.

Have fixed a couple of new/delete[] problems which existed as a result.

To use the MemoryManager to track memory usage simply add
-DOSG_USE_MEMEORY_TRACKING to the compile line.

Have yet to move the osg from using new to osgNew, will do this next.

VisualStudio/osg/osg.dsp

@@ -225,6 +225,10 @@ SOURCE=..\..\src\osg\Material.cpp
 # End Source File
 # Begin Source File
 
+SOURCE=..\..\src\osg\MemoryManager.cpp
+# End Source File
+# Begin Source File
+
 SOURCE=..\..\src\osg\Matrix.cpp
 # End Source File
 # Begin Source File
@@ -485,6 +489,10 @@ SOURCE=..\..\Include\Osg\Material
 # End Source File
 # Begin Source File
 
+SOURCE=..\..\Include\Osg\MemoryManager
+# End Source File
+# Begin Source File
+
 SOURCE=..\..\include\osg\Math
 # End Source File
 # Begin Source File