snf: Fix the handling of bounded repetition.

star_normal_form() used to be called under bounded
repetitions like [*0..4], but some of these rewritings
are only correct for [*0..].  For instance
     (a*|1)[*]      can be rewritten to    1[*]
but  (a*|1)[*0..1]  cannot be rewritten to 1[*0..1]
it would be correct to rewrite the latter as (a[+]|1)[*0..1],
canceling the empty word in a*.

Also (a*;b*)[*]     can be rewritten to    (a|b)[*]
but  (a*;b*)[*0..1]  cannot be rewritten to (a|b)[*0..1]
and it cannot either be rewritten to (a[+]|b[+])[*0..1].

This patch introduces a new function to implement
rewritings under bounded repetition.

* src/ltlvisit/snf.hh, src/ltlvisit/snf.cc (star_normal_form_unbounded):
New function.
* src/ltlvisit/simplify.cc: Use it.
* src/ltltest/reduccmp.test: Add tests.
* doc/tl/tl.tex: Document the rewritings implemented.

src/ltltest/reduccmp.test

@@ -364,6 +364,9 @@ for x in ../reduccmp ../reductaustr; do
      run 0 $x '{(a;c*;d)|(b;c)}' '(a & X(c W d)) | (b & Xc)'
      run 0 $x '!{(a;c*;d)|(b;c)}' '(X(!c M !d) | !a) & (X!c | !b)'
      run 0 $x '(Xc R b) & (Xc W 0)' 'b & XGc'
+     run 0 $x '{{c*|1}[*0..1]}<>-> v' '{{c[+]|1}[*0..1]}<>-> v'
+     run 0 $x '{{b*;c*}[*3..5]}<>-> v' '{{b*;c*}[*0..5]} <>-> v'
+     run 0 $x '{{b*&c*}[*3..5]}<>-> v' '{{b[+]|c[+]}[*0..5]} <>-> v'
 
      # not reduced
      run 0 $x '{a;(b[*2..4];c*;([*0]+{d;e}))*}!' \