In order to fix issue #47 I've added a custom eventstream
to termui that will deregister its own eventstream.
This will ensure me that the events will not be sent to
termui's (unbuffered) event channel and will be picked
up by the buffered termbox channel of slack-term.
Fixes#47
This should alleviate some problems with using the application and
getting the error:
panic: runtime error: slice bounds out of range
However, I'm still able to trigger this event when scrolling
the mouse wheel.
Fixes#47
