Release Spot 2.8.7

* NEWS, configure.ac, doc/org/setup.org: Update.

NEWS

@@ -1,11 +1,9 @@
-New in spot 2.8.6.dev (not yet released)
-
-  Nothing yet.
+New in spot 2.8.7 (2019-03-13)
 
   Bugs fixed:
 
   - Building a product between two complete automata where one operand
-    had false acceptance could create a incomplete automaton
+    had false acceptance could create an incomplete automaton
     incorrectly tagged as complete, causing the print_hoa() function
     to raise an exception.
 
@@ -18,6 +16,18 @@ New in spot 2.8.6.dev (not yet released)
     wrong.  This could in turn cause segfaults or infinite loops while
     running autcross or autfilt --stats=%w.
 
+  - The generic emptiness check used a suboptimal selection of "Fin"
+    to remove, not matching the correct line in our ATVA'19 paper.
+    This could cause superfluous recursive calls, however benchmarks
+    have shown the difference to be insignificant in practice.
+
+  - The sl(), and sl2() functions for computing the "self-loopization"
+    of an automaton, and used for instance in algorithms for computing
+    proof of stutter-sensitiveness (e.g., in our web application),
+    were incorrect when applied on automata with "t" acceptance (or
+    more generaly, any automaton where a cycle without mark is
+    accepting).
+
   - ltlcross was not diagnosing write errors associated to
     options --grind=FILENAME and --save-bogus=FILENAME.