fix wxTextCtrl::Replace() under wxGTK; added unit test for it and describe its effect on the insertion point

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@57253 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

tests/controls/textentrytest.h

@@ -37,12 +37,14 @@ protected:
         CPPUNIT_TEST( SetValue ); \
         CPPUNIT_TEST( TextChangeEvents ); \
         CPPUNIT_TEST( Selection ); \
-        CPPUNIT_TEST( InsertionPoint )
+        CPPUNIT_TEST( InsertionPoint ); \
+        CPPUNIT_TEST( Replace )
 
     void SetValue();
     void TextChangeEvents();
     void Selection();
     void InsertionPoint();
+    void Replace();
 
 private:
     // Selection() test helper: verify that selection is as described by the