[dwm] master size for each tag patch

Hi,

I was thinking about having different master size for each tag.
E.g. with xterms, I would like to be master close to 50%, but on the
other hand I would like to have browser somewhere around 80%, so that I can
have a dictionary app open besides it that doesn't take up much horizontal
space.
But then I thought, what if I am viewing more than one tag at once? Whose
master size would be preferred? And whose resized?
Well, things are getting complicated.
The best thing that I could think of is that you would change some
other master variable that would be used specifically when viewing more than
one tag.

So I tried to write my first patch for dwm and have to say it worked out
excelently.
I also have to thank Anselm and Sander for the great job on dwm, because
patching it was a real delight :-)

So please try it out and tell me if it works correctly.

Cheers.