The actual rules are a bit more complex:
a & X(G(a&b...)&c...) = Ga & X(G(b...)&c...)
a | X(Fa | c) = F(a) | c
with the second rule being applied only if all XF can
be removed.  See the documentation for an example.

* src/ltlvisit/simplify.cc: Implement these new rules.
* doc/tl/tl.tex: Document them.
* src/ltltest/reduccmp.test: Add test cases.