Use KNotify in kwrited instead of popping up a QTextEdit.

Also, fix various other minor things in kwrited:
* Remove the useless includes.
* Use KPtyDevice instead of KPty and direct system calls.
* Remove the bell character together with carriage return from incoming messages.
* Change the component name from "konsole" to "kwrited".
* Cleanup out-of-date comments and commented-out code.
* puts() becomes kDebug().