removed inheritance in SubInstrTab

Author: Barbara Frosik

.gitignore

@@ -1,3 +1,5 @@
+example_workspace/*
+
 # Byte-compiled / optimized / DLL files
 __pycache__/
 *.py[cod]

.idea/.gitignore

@@ -619,14 +619,7 @@ def set_res_dir(self):
             msg_window('please select valid results directory')
 
 
-class SubInstrTab(QWidget):
-    def __init__(self, parent=None):
-        """
-        Constructor, initializes the tabs.
-        """
-        super(SubInstrTab, self).__init__(parent)
-
-
+class SubInstrTab():
     def init(self, instr_tab, main_window):
         """
         Creates and initializes the 'Instrument' tab.