split worlds.lisp into mainworlds.lisp and other-worlds.lisp and remove 'body base class
fix bug in stellar-size generation for non-primary stars
star generation for systems
fix dependency.

stars needs other-worlds to be compiled first for the brown-dwarf definition.
add close, near, and far star definitions

Also minor bugfixes in stellar generation
add world-type support

also assorted small fixes.
world-type support for mainworlds