Warning since 7efae3f8 yices doesn't
work with real since in assoc_mul_div a variable is the denominator.
Yices refuse that.

updated DTD

because it is incompatible with the session system

instead of $libdir/plugins. We have no other binary components.

also remove the trailing whitespaces. Dear colleagues,
could you please configure your Emacsen correctly?

small modifs in the manual