Continued:

Continued:
- Added new class field $urlSourceInstance (What?! Not added before?) with
  interface UrlSource as type-hint
- Removed deprecated classes/include files
- Added some "life" to FiFoFileStack as this class may happen the same was the
  memory-based counter part FiFoStack. Still the BaseFileStack needs a lot
  enhancement (unfinished).

Signed-off-by: Roland Häder <roland@mxchange.org>