Attaches an e93 buffer to a Tcl output channel. The Tcl channel will be created if necessary.
From that point on, data written to that Tcl channel will be inserted in the e93 buffer.
If no bufferName is given the Tcl channel will be attached to the
buffer of the e93 Window that is active at the time data is written to the channel.
Only one buffer may be attached to any given channel. Any e93 buffer that was attached to the Tcl channel prior
to this call will disconnected.