org: work around issue with Org 9.2

See the following email
http://lists.gnu.org/archive/html/emacs-orgmode/2019-01/msg00226.html

* doc/org/tut24.org, doc/org/tut51.org: Export the output of
noweb-based block without ':export results' or ':export both'.
* doc/org/spot.css: Add style for src-text.

doc/org/spot.css

@@ -19,6 +19,7 @@ body a{color:#008181}
 pre.src{padding-top:8px;border-left-style:solid;border-color:#00adad;overflow:auto}
 pre.src-hoa{padding-top:8px;border-left-style:solid;border-color:#d70079;overflow:auto}
 pre.example{border-left-style:solid;border-color:#d70079}
+pre.src-text{border-left-style:solid;border-color:#d70079}
 pre.src:before{border:none;border-bottom-style:solid;border-color:#00adad;top:0px;}
 pre.src-python:before{content:'Python'}
 pre.src-C\+\+:before{content:'C++'}

doc/org/tut24.org

@@ -54,7 +54,7 @@ and that we run the following code, similar to what we did in the
 [[file:tut21.org][custom automaton printer]].
 
 #+NAME: nonalt-body
-#+BEGIN_SRC C++ :exports code :noweb strip-export
+#+BEGIN_SRC C++
 std::cout << "Initial state: " << aut->get_init_state_number() << '\n';
 
 const spot::bdd_dict_ptr& dict = aut->get_dict();
@@ -72,7 +72,7 @@ for (unsigned s = 0; s < n; ++s)
 #+END_SRC
 
 #+NAME: nonalt-main
-#+BEGIN_SRC C++ :exports none :noweb strip-export
+#+BEGIN_SRC C++ :exports none
   #include <string>
   #include <iostream>
   #include <spot/parseaut/public.hh>
@@ -98,7 +98,7 @@ for (unsigned s = 0; s < n; ++s)
 #+END_SRC
 
 #+NAME: nonalt-one
-#+BEGIN_SRC C++ :exports results :noweb strip-export :results verbatim
+#+BEGIN_SRC C++ :exports none :noweb strip-export :results verbatim
   <<nonalt-main>>
   void custom_print(spot::twa_graph_ptr& aut)
   {
@@ -106,28 +106,11 @@ for (unsigned s = 0; s < n; ++s)
   }
 #+END_SRC
 
-#+RESULTS: nonalt-one
+# temporary fix for an issue in Org 9.2, see
-#+begin_example
+# http://lists.gnu.org/archive/html/emacs-orgmode/2019-01/msg00226.html
-Initial state: 4294967295
+#+BEGIN_SRC text :noweb yes
-State 0:
+<<nonalt-one()>>
-  edge(0 -> 0)
+#+END_SRC
-    label = a
-    acc sets = {}
-  edge(0 -> 4294967295)
-    label = !a
-    acc sets = {}
-State 1:
-  edge(1 -> 1)
-    label = !a
-    acc sets = {0}
-  edge(1 -> 2)
-    label = a
-    acc sets = {}
-State 2:
-  edge(2 -> 2)
-    label = 1
-    acc sets = {}
-#+end_example
 
 This output seems correct only for non-universal edges.  The reason is
 that Spot always store all edges as a tuple (src,dst,label,acc sets),
@@ -153,7 +136,7 @@ unconditionally.  In this example, we simply call =is_univ_dest()= to
 decide whether to enclose the destinations in braces.
 
 #+NAME: nonalt-body2
-#+BEGIN_SRC C++ :exports code :noweb strip-export
+#+BEGIN_SRC C++
   unsigned init = aut->get_init_state_number();
   std::cout << "Initial state:";
   if (aut->is_univ_dest(init))
@@ -186,7 +169,7 @@ decide whether to enclose the destinations in braces.
 #+END_SRC
 
 #+NAME: nonalt-two
-#+BEGIN_SRC C++ :exports results :noweb strip-export :results verbatim
+#+BEGIN_SRC C++ :exports none :noweb strip-export :results verbatim
   <<nonalt-main>>
   void custom_print(spot::twa_graph_ptr& aut)
   {
@@ -194,28 +177,11 @@ decide whether to enclose the destinations in braces.
   }
 #+END_SRC
 
-#+RESULTS: nonalt-two
+# temporary fix for an issue in Org 9.2, see
-#+begin_example
+# http://lists.gnu.org/archive/html/emacs-orgmode/2019-01/msg00226.html
-Initial state: { 0 1 }
+#+BEGIN_SRC text :noweb yes
-State 0:
+<<nonalt-two()>>
-  edge(0 -> 0)
+#+END_SRC
-    label = a
-    acc sets = {}
-  edge(0 -> { 0 1 })
-    label = !a
-    acc sets = {}
-State 1:
-  edge(1 -> 1)
-    label = !a
-    acc sets = {0}
-  edge(1 -> 2)
-    label = a
-    acc sets = {}
-State 2:
-  edge(2 -> 2)
-    label = 1
-    acc sets = {}
-#+end_example
 
 * Python
 

doc/org/tut51.org

@@ -408,64 +408,40 @@ check whether the output is empty.  If it is not, that means we have
 found a counterexample.  Here is some code that would show this
 counterexample:
 
-#+NAME: demo-2-aux
+#+NAME: demo-2
-#+BEGIN_SRC C++ :exports none :noweb strip-export
+#+BEGIN_SRC C++ :exports code :noweb strip-export :results verbatim
- <<headers>>
+#include <spot/tl/parse.hh>
- <<demo-state>>
+#include <spot/twaalgos/translate.hh>
- <<demo-iterator>>
+#include <spot/twa/twaproduct.hh>
- <<demo-kripke>>
+#include <spot/twaalgos/emptiness.hh>
- <<demo-succ-iter-2>>
+<<demo-1-aux>>
+int main()
+{
+   auto d = spot::make_bdd_dict();
+
+   // Parse the input formula.
+   spot::parsed_formula pf = spot::parse_infix_psl("GF(odd_x) -> GF(odd_y)");
+   if (pf.format_errors(std::cerr))
+     return 1;
+
+   // Translate its negation.
+   spot::formula f = spot::formula::Not(pf.f);
+   spot::twa_graph_ptr af = spot::translator(d).run(f);
+
+   // Find a run of or demo_kripke that intersects af.
+   auto k = std::make_shared<demo_kripke>(d);
+   if (auto run = k->intersecting_run(af))
+     std::cout << "formula is violated by the following run:\n" << *run;
+   else
+     std::cout << "formula is verified\n";
+}
 #+END_SRC
 
- #+NAME: demo-2
+# temporary fix for an issue in Org 9.2, see
- #+BEGIN_SRC C++ :exports both :noweb strip-export :results verbatim
+# http://lists.gnu.org/archive/html/emacs-orgmode/2019-01/msg00226.html
-   #include <spot/tl/parse.hh>
+#+BEGIN_SRC text :noweb yes
-   #include <spot/twaalgos/translate.hh>
+<<demo-2()>>
-   #include <spot/twa/twaproduct.hh>
+#+END_SRC
-   #include <spot/twaalgos/emptiness.hh>
-   <<demo-2-aux>>
-   int main()
-   {
-      auto d = spot::make_bdd_dict();
-
-      // Parse the input formula.
-      spot::parsed_formula pf = spot::parse_infix_psl("GF(odd_x) -> GF(odd_y)");
-      if (pf.format_errors(std::cerr))
-        return 1;
-
-      // Translate its negation.
-      spot::formula f = spot::formula::Not(pf.f);
-      spot::twa_graph_ptr af = spot::translator(d).run(f);
-
-      // Find a run of or demo_kripke that intersects af.
-      auto k = std::make_shared<demo_kripke>(d);
-      if (auto run = k->intersecting_run(af))
-        std::cout << "formula is violated by the following run:\n" << *run;
-      else
-        std::cout << "formula is verified\n";
-   }
- #+END_SRC
-
- #+RESULTS: demo-2
- #+begin_example
- formula is violated by the following run:
- Prefix:
-   (x = 0, y = 0)
-   |  !odd_x & !odd_y
-   (x = 1, y = 0)
-   |  odd_x & !odd_y
-   (x = 1, y = 1)
-   |  odd_x & odd_y
-   (x = 1, y = 2)
-   |  odd_x & !odd_y
- Cycle:
-   (x = 2, y = 2)
-   |  !odd_x & !odd_y
-   (x = 0, y = 2)
-   |  !odd_x & !odd_y
-   (x = 1, y = 2)
-   |  odd_x & !odd_y
-#+end_example
 
 With a small variant of the above code, we could also display the
 counterexample on the state space, but only because our state space is