--enable-gtk-doc

[Owen Taylor <otaylor redhat com>]

I'd like to make --disable-gtk-doc the default and add
--enable-gtk-doc to autogen.sh.

Reasons for this:

 - Somebody building from a tarball has no reason to rebuild
   the docs in almost all cases.

 - Rebuilding the docs is slow. Really slow.

 - Getting Jade setup can be a nightmare if you don't already
   have a setup.

 - We are bad about putting out gtk-doc realeases in sync
   with GTK+ releases, so you often have to get gtk-doc
   from CVS to build with --enable-gtk-doc.

[ Note that --enable-gtk-doc does check for gtk-doc, so if
  you don't have gtk-doc installed at all, you are fine 
  currently. ]
  
Disadvantages:

 - If you are developing gtk+, you'll have to remember
   to add --enable-gtk-doc, unless you use autogen.sh.

   (How many people develop GTK+ and don't use autogen.sh? 
   Windows developers don't count since I'd imagine that
   getting the gtk-doc stuff to build on windows would be
   as much fun as having your beard plucked out hair by
   hair.) 

Opinions?
                                        Owen