[edfscan] add get_range function

tomoscan/esrf/edfscan.py

@@ -661,3 +661,9 @@ class EDFTomoScan(TomoScanBase):
                     return info
 
         return None
+
+    def get_range(self):
+        if self.path is not None:
+            return self.get_scan_range(self.path)
+        else:
+            return None