rename src/ as spot/ and use include <spot/...>

* NEWS: Mention the change.
* src/: Rename as ...
* spot/: ... this, adjust all headers to include <spot/...> instead of
"...", and adjust all Makefile.am to search headers from the top-level
directory.
* HACKING: Add conventions about #include.
* spot/sanity/style.test: Add a few more grep to catch cases
that do not follow these conventions.
* .gitignore, Makefile.am, README, bench/stutter/Makefile.am,
bench/stutter/stutter_invariance_formulas.cc,
bench/stutter/stutter_invariance_randomgraph.cc, configure.ac,
debian/rules, doc/Doxyfile.in, doc/Makefile.am,
doc/org/.dir-locals.el.in, doc/org/g++wrap.in, doc/org/init.el.in,
doc/org/tut01.org, doc/org/tut02.org, doc/org/tut03.org,
doc/org/tut10.org, doc/org/tut20.org, doc/org/tut21.org,
doc/org/tut22.org, doc/org/tut30.org, iface/ltsmin/Makefile.am,
iface/ltsmin/kripke.test, iface/ltsmin/ltsmin.cc,
iface/ltsmin/ltsmin.hh, iface/ltsmin/modelcheck.cc,
wrap/python/Makefile.am, wrap/python/ajax/spotcgi.in,
wrap/python/spot_impl.i, wrap/python/tests/ltl2tgba.py,
wrap/python/tests/randgen.py, wrap/python/tests/run.in: Adjust.

bench/stutter/Makefile.am

@@ -17,12 +17,12 @@
 ## You should have received a copy of the GNU General Public License
 ## along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-AM_CPPFLAGS = -I$(top_srcdir)/src -I$(top_builddir)/src $(BUDDY_CPPFLAGS) \
+AM_CPPFLAGS = -I$(top_builddir) -I$(top_srcdir) $(BUDDY_CPPFLAGS) \
               -I$(top_builddir)/lib -I$(top_srcdir)/lib
 AM_CXXFLAGS = $(WARNING_CXXFLAGS)
 
-LDADD = $(top_builddir)/src/bin/libcommon.a ../../lib/libgnu.la	\
-        ../../src/libspot.la
+LDADD = $(top_builddir)/spot/bin/libcommon.a ../../lib/libgnu.la	\
+        ../../spot/libspot.la
 
 bin_PROGRAMS = stutter_invariance_randomgraph \
 	       stutter_invariance_formulas