autfilt: add option --separate-edges

* bin/autfilt.cc: Implement it.
* tests/core/split.test: Test it.
* doc/org/tut25.org: Demonstrate it.
* NEWS: Mention it.

NEWS

@@ -1,5 +1,11 @@
 New in spot 2.11.6.dev  (not yet released)
 
+  Documentation:
+
+  - https://spot.lre.epita.fr/tut25.html is a new example showing
+    how to print an automaton in the "BA format" (used by Rabbit
+    and other tools).
+
   Command-line tools:
 
   - In places that accept format strings with '%' sequences, like
@@ -19,6 +25,10 @@ New in spot 2.11.6.dev  (not yet released)
     and its negation is already a basis).  This can help reducing the
     size of large HOA files.
 
+  - autfilt learned --separate-edges, to split the labels of
+    the automaton using a basis of disjoint labels.  See
+    https://spot.lre.epita.fr/tut25.html for some motivation.
+
   - ltlfilt has a new option --relabel-overlapping-bool=abc|pnn that
     will replace boolean subformulas by fresh atomic propositions even
     if those subformulas share atomic propositions.
@@ -204,11 +214,6 @@ New in spot 2.11.6.dev  (not yet released)
     This version of Spot now declares its svg outputs as HTML to
     prevent Jypyter from wrapping them is images.
 
-  Documentation:
-
-  - https://spot.lre.epita.fr/tut25.html is a new example showing
-    how to print an automaton in the "BA format" (used by Rabbit).
-
   Bugs fixed:
 
   - tgba_determinize()'s use_simulation option would cause it to