Add a menu entry for the (possibly unnamed) first style-specification.

Set up a comprehensive initial structure for characteristics menues. 
How much is useful? Find a good menu structure. `characteristics.dsl'
is a starting point.

Perhaps the specification of the menu structure should be separated from
the specification of values and other information (to make integration of
menu hierarchies for characteristics and variables from separate style-sheets
possible).

Make "Compiling" disappear from the mode line again.

Follow <external-specifications> when parsing the customize info.

Make the "File Options" submenu a proper submenu instead of a popup.

Add value indicators to the variable menu entries under "Customize style
sheet" (in addition to the little "*" marking the current value in the
values popup, since at that point it is too late to go back in the menu
hierarchy if you discover that the value is ok.)

Implement the dynamic menues properly using update-menu-bar-hook. I could not 
get it to work so far.

Test everything. 



