Release Spot 0.9.1

* configure.ac, NEWS: Bump version number.

NEWS

-New in spot 0.9a:
+New in spot 0.9.1 (2012-05-23):
 
-  * The version of LBTT we distribute include a patch from Tomáš
+  * The version of LBTT we distribute includes a patch from Tomáš
     Babiak to count the number of non-deterministic states, and the
     number of deterministic automata produced.
     See lbtt/NEWS for the list of other differences with the original

configure.ac

@@ -22,7 +22,7 @@
 # 02111-1307, USA.
 
 AC_PREREQ([2.61])
-AC_INIT([spot], [0.9a], [spot@lrde.epita.fr])
+AC_INIT([spot], [0.9.1], [spot@lrde.epita.fr])
 AC_CONFIG_AUX_DIR([tools])
 AC_CONFIG_MACRO_DIR([m4])
 AM_INIT_AUTOMAKE([1.11 gnu tar-ustar color-tests parallel-tests])