style: Fix PEP8 blank lines issues in Python files

Done with `autopep8 --select=E3,W3`, fixes:

- E301 - Add missing blank line.
- E302 - Add missing 2 blank lines.
- E303 - Remove extra blank lines.
- E304 - Remove blank line following function decorator.
- E309 - Add missing blank line.
- W391 - Remove trailing blank lines.

tools/scripts/addheader.py

@@ -56,7 +56,6 @@ while (fname != ""):
     else:
         text = header.replace("$filename", fsingle)
 
-
     while (l != ""):
         if ((l.find("//") != 0 and l.find("/*") != 0 and l.strip() != "") or bc):
             text += l
@@ -69,4 +68,3 @@ while (fname != ""):
     fr.close()
     # print(text)
     fname = f.readline()
-