when the user was prompted to choose a tree to mirror, it would mirror
the wrong one

this is mainly because users shouldnt be encouraged to use j/k, but
rather they should use the shortcuts... this is faster and stops the
menu from being re-rendered so often (which looks shithouse since he
screen is being ":redraw!"n)

There was an error in the function which prevented Windows paths
from being properly decoded.  This error was causing the ".. (up a dir)"
feature to fail due to an unhandled Invalid Argument exception.

Signed-off-by: Tim Henigan <tim.henigan@gmail.com>

Signed-off-by: Martin Grenfell <martin_grenfell@msn.com>

remove the old "OS" format option and introduce "UI" (which is the old
default)

patch from Bryan Venteicher

now we have a slight flicker on console vim, but the rendering engine is
more robust in general and should work across different OSs/versions of
vim

now everything uses the equivalent of Path#str(0)