wdisp: a pedestrian command window waitbar

Creates the equivalent of WAITBAR in the command window.
See:
help wdisp
for a self-explanatory example - or type:

t='-\|/';
for i=1:40
tl=wdisp( 0,sprintf('time %c %s',t(rem(i,4)+1),datestr(now)));
% do some computation(s)
tl=wdisp(tl,sprintf('count %3d %s',i,repmat('.',1,i)));
% do more computation(s)
pause(.1);
tl=wdisp(tl);
end