* src/ltlast/bunop.hh (one_star): New static method building 1[*].
* src/ltlast/bunop.cc (bunop::~bunop, bunop::instance_count): Adjust.
* src/ltlast/multop.cc: Implement the trivial rewriting.
* src/ltlast/multop.hh, doc/tl/tl.tex: Document it.
* src/ltltest/equals.test: Test it.