- Add pre-support for "enable extensions".
- Load CMD settings at startup from the registry (from HKLM and HKCU
  Software\\Microsoft\\Command Processor reg key), as done by Windows' CMD.EXE.
- Add support for CMD.EXE /E(:OFF), /X, /Y command-line switches.
- Correctly set the console colors when using CMD.EXE /T: switch.
- Start support for two control characters for the completion: the standard CompletionChar
  and the PathCompletionChar (if one desires to autocomplete *just* directory
  names -- or associated -- but not everything), as Windows' CMD.EXE offers.

svn path=/trunk/; revision=75997