Added __len__ function do OBIViews that returns the line count

python/obitools3/obidms/_obidms.pyx

@@ -449,6 +449,10 @@ cdef class OBIView :
         return (column_name in self.columns)
     
     
+    def __len__(self):
+        return(self.pointer.infos.line_count)
+    
+    
     def __str__(self) :
         cdef OBIView_line line
         cdef str to_print