extract (and expand and clean up and document) the header window implementation used inside the generic wxDataViewCtrl in a separate wxHeaderCtrl class which could be reused in (generic) wxListCtrl and, most importantly, wxGrid later

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@57093 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

tests/test_test_gui.dsp

@@ -257,6 +257,10 @@ SOURCE=.\misc\guifuncs.cpp
 # End Source File
 # Begin Source File
 
+SOURCE=.\controls\headerctrltest.cpp
+# End Source File
+# Begin Source File
+
 SOURCE=.\html\htmlwindow.cpp
 # End Source File
 # Begin Source File