A start at adding "tiling inside quadrants" to dmg-quadrants.jl

[Pat Regan <thehead patshead com>]

I have a barely working attempt at making my tiling idea work.  It still 
needs some hooks to rearrange the tiling when a window is closed or 
moved, so it isn't terribly functional yet.

I tacked on an extra option to the items in the dmg-quadrants variable. 
 "none" means it works just like it always did.  "vertical" tiles 
windows vertically inside the quadrant, "horizontal" is not implemented.

If a quadrant is marked "vertical," the first window pushed into the 
quadrant will occupy the whole quadrant.  When a second window is pushed 
into the quadrant, each window will be resized to half the height of the 
quadrant and positioned appropriately.

After watching it working properly, I had a new thought.  I'm thinking 
maybe instead of having picking and choosing which quadrants to tile 
that there should be a function that tiles the windows in an existing 
quadrant.

I through a temporary copy of my work in progress up on my web server:

http://patshead.com/tmp/dmg-quadrants.jl

Again, it isn't very usable right now.  It really only demonstrates the 
thought I am chasing after.

Pat