feat(TextEdit): add clear method (#458)

libs/pyTermTk/TermTk/TTkGui/textdocument.py

@@ -238,6 +238,9 @@ class TTkTextDocument():
     def characterCount(self):
         return sum([len[x] for x in self._dataLines])+self.lineCount()
 
+    def clear(self):
+        self.setText(self._default_init_text)
+
     def setText(self, text:TTkStringType) -> None:
         remLines = len(self._dataLines)
         if not isinstance(text, str) and not isinstance(text,TTkString):

libs/pyTermTk/TermTk/TTkWidgets/texedit.py

@@ -619,7 +619,9 @@ class TTkTextEditView(TTkAbstractScrollView):
 
             The undo/redo history is also cleared.
         '''
-        self.setText(TTkString())
+        self.viewMoveTo(0, 0)
+        self._textDocument.clear()
+        self._updateSize()
 
     def lineWrapMode(self) -> TTkK.LineWrapMode:
         '''