Unify MonoBook <head> generation with legacy skins
This was less work than I thought it would be. The only possible
practical difference in MonoBook should be that some IE fixes are moved
down; at a glance, I don't see how this would hurt anything, but if it
does then some more hacks can be added to move them back up.
A bunch of whitespace was changed in both MonoBook and legacy skins.
Legacy skins had some stuff moved around in the <head>, but mainly to
better match MonoBook, so they should work better if anything, not
worse. dir= was added to the <body> in legacy skins, matching MonoBook.
There should be no other practical differences.
I would strongly encourage people to port the Modern and Vector skins to
at least share the <head>-generation code like this. I'd even more
strongly encourage people to totally rewrite the skin system, but that's
a bigger job. :)