CppUnit - C++ port of JUnit Code

* src/cppunit/PlugInManager.cpp: added two methods to use the plug-in
interface for Xml Outputter hooks.

* include/cppunit/plugin/TestPlugIn.h: added two methods to the plug-in
interface for Xml Outputter hooks.

* include/cppunit/plugin/TestPlugInAdapter.h:
* src/cppunit/plugin/TestPlugInAdapter.cpp: renamed TestPlugInDefaultImpl.
Added empty implementation for Xml outputter hook methods.

* include/cppunit/tools/StringTools.h:
* src/cppunit/tools/StringTools.cpp: added. Functions to manipulate string
(conversion, wrapping...)

* include/cppunit/tools/XmlElement.h:
* src/cppunit/XmlElement.cpp: renamed addNode() to addElement(). Added
methods to walk and modify XmlElement (for hook). Added documentation.
Use StringTools.

* include/cppunit/XmlOutputter.h:
* src/cppunit/XmlOutputter.cpp: added hook calls & management.

* include/cppunit/XmlOutputterHook.h:
* src/cppunit/XmlOutputterHook.cpp: added. Hook to customize XML output.

* src/DllPlugInTester/DllPlugInTester.cpp: call plug-in XmlOutputterHook
when writing XML output. Modified so that memory is freed before
unloading the test plug-in (caused crash when freeing the XmlDocument).

* examples/ReadMe.txt:
* examples/ClockerPlugIn/ReadMe.txt: added details about the plug-in
(usage, xml content...)

* examples/ClockerPlugIn/ClockerModel.h:
* examples/ClockerPlugIn/ClockerModel.cpp: extracted from ClockerListener.
Represents the test hierarchy and tracked time for each test.

* examples/ClockerPlugIn/ClockerListener.h:
* examples/ClockerPlugIn/ClockerListener.cpp: extracted test hierarchy
tracking to ClockerModel. Replaced the 'flat' view option with a 'text'
option to print the timed test tree to stdout.

* examples/ClockerPlugIn/ClockerPlugIn.cpp: updated to hook the XML
output and use the new classes.

* examples/ClockerPlugIn/ClockerXmlHook.h:
* examples/ClockerPlugIn/ClockerXmlHook.cpp: added. XmlOutputterHook to
includes the timed test hierarchy and test timing in the XML output.

* examples/cppunittest/XmlElementTest.h:
* examples/cppunittest/XmlElementTest.cpp: added new test cases.

* examples/cppunittest/XmlOutputterTest.h:
* examples/cppunittest/XmlOutputterTest.cpp: added tests for
XmlOutputterHook.