text: Title: Potential typo bug in pywinauto top-level file.
  Body: Line 91 in `pywinauto/__init__.py` we have this code which looks like a typo ("ElementNotFoundError = findwindows.ElementNotFoundError" is duplicated as is), wasn't it supposed to be WindowNotFoundError instead ?
  
  ```
      WindowAmbiguousError = findwindows.WindowAmbiguousError
      ElementNotFoundError = findwindows.ElementNotFoundError
  
      if UIA_support:
          ElementNotFoundError = findwindows.ElementNotFoundError
          ElementAmbiguousError = findwindows.ElementAmbiguousError
  ```