Major update of all demo programs to use new PEP8 bindings, etc

DemoPrograms/Demo_Hello_World.py

@@ -1,15 +1,18 @@
 import PySimpleGUI as sg
 
 """
-    Oh yes, the classic "Hello World".  The problem is that you
+    Oh yes, the classic "Hello World". The problem is that you
     can do it so many ways using PySimpleGUI
 """
 
-sg.PopupNoButtons('Hello World')         # the single line
+sg.popup_no_buttons('Hello World')         # the single line
 
-sg.Window('Hello world', [[sg.Text('Hello World')]]).Read()    # single line using a real window
+# single line using a real window
+sg.Window('Hello world', [[sg.Text('Hello World')]]).read()
 
 # This is a "Traditional" PySimpleGUI window code. First make a layout, then a window, the read it
 layout = [[sg.Text('Hello World')]]
 window = sg.Window('Hello world', layout)
-event, values = window.Read()
+event, values = window.read()
+
+window.close()