* Move the libedit interface there and provide nicer to use methods.
* Also start adding utility methods for the input loop. It is going to
manage all interactions of the input loop with outside events.
* Fix the "quit" command. The user is now prompted what to do with the
debugged team and the input loop thread avoids reentering the input
loop.
* UserInterface::SynchronouslyAskUser() is now allowed to return -1 to
indicate that the user cannot be asked at this point for whatever
reason. The caller needs to handle that case.
* UserInterfaceListener::UserInterfaceQuitRequested(): Add new parameter
"quitOption" to specify what is supposed to happen. The previous
behavior (ask user) is only one of the options. The others are to kill
the debugged team or to resume it.
There's an input loop thread which reads and parses command lines and
the infrastructure for registering and executing commands. Currently
only "help" and "quit" commands are implemented.