Add a class for parsing simple markup.

This code is not used anywhere yet, this commit only adds the parser for the
markup and the related classes as well as the corresponding unit test.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67048 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

tests/test_test_gui.dsp

@@ -393,6 +393,10 @@ SOURCE=.\controls\listviewtest.cpp
 # End Source File
 # Begin Source File
 
+SOURCE=.\controls\markuptest.cpp
+# End Source File
+# Begin Source File
+
 SOURCE=.\graphics\measuring.cpp
 # End Source File
 # Begin Source File