This fix is not perfect, in that it will not fix every terminal that has
automargin support, but it fixes the *vast* majority of them by eliminating
the hacky workaround for the automargin - essentially using the rmam capability
to disable automatic wrapping at the margin.
This adds optional MouseFlags that can be used to adjust what is
tracked for mouse reporting (leaving the other modes to be handled
by the terminal.) This should work on all XTerm style terminals,
but on Windows we have no way to be selective here.
