Log Message:
Update to dvtm-0.4.1. Contributed by Leonardo Taccari.

* Cursor key mode switching (this fixes arrow keys in vim)
* Characters following an escape are passed to the underlying
  application, this fixes ALT+<n> key combination as used by
  irssi
* A hack to make the keypad sort of work with putty
* Mouse support is now compile time selectable
* Destroy clients when an IO-error occurs
* Correct signal handling (save and restore errno)
* Destroy clients cleanly, prevent zombies
* Added a note about copy & paste to the manual page (use
  SHIFT while selecting or pasting text)
* Some source code formatting fixes