* src/ltlast/bunop.cc (bunop::format): Output [*1..] as [+].
* src/ltlvisit/tostring.cc: Output "a*" as "a[*]" for consistency.
* src/ltlparse/ltlparse.yy, src/ltlparse/ltlscan.ll: Recognize [+].
* src/ltltest/tostring.test, src/ltltest/equals.test,
src/tgbatest/ltl2tgba.test: More tests.