python: add some doc & tests for the acceptance bindings

* wrap/python/tests/acc_cond.ipynb: New file.
* wrap/python/tests/Makefile.am, doc/org/tut.org: Add it.
* wrap/python/spot_impl.i: Add printer for acc_cond::mark_t.

doc/org/tut.org

@@ -50,6 +50,8 @@ real notebooks instead.
   generated random automata, which are displayed in a table before and
   after acceptance simplification
 - [[https://spot.lrde.epita.fr/ipynb/accparse.html][accparse.ipynb]] exercises the acceptance condition parser
+- [[https://spot.lrde.epita.fr/ipynb/acc_cond.html][acc_cond.ipynb]] documents the interface for manipulating acceptance
+  conditions
 - [[https://spot.lrde.epita.fr/ipynb/randltl.html][randltl.ipynb]] demonstrates a Python-version of [[file:randltl.org][=randltl=]]
 - [[https://spot.lrde.epita.fr/ipynb/decompose.html][decompose.ipynb]] illustrates the =decompose_strength()= function
 - [[https://spot.lrde.epita.fr/ipynb/testingaut.html][testingaut.ipynb]] shows the step necessary to build a testing

wrap/python/spot_impl.i

@@ -441,14 +441,6 @@ namespace std {
   std::string __str__() { return spot::str_psl(*self); }
 }
 
-%extend spot::acc_cond::mark_t {
-  // http://comments.gmane.org/gmane.comp.programming.swig/14822
-  mark_t(const std::vector<unsigned>& f)
-  {
-    return new spot::acc_cond::mark_t(f.begin(), f.end());
-  }
-}
-
 %extend spot::twa {
   void set_name(std::string name)
   {
@@ -487,12 +479,25 @@ namespace std {
 }
 
 %extend spot::acc_cond::mark_t {
+  // http://comments.gmane.org/gmane.comp.programming.swig/14822
+  mark_t(const std::vector<unsigned>& f)
+  {
+    return new spot::acc_cond::mark_t(f.begin(), f.end());
+  }
+
   std::string __str__()
   {
     std::ostringstream os;
     os << *self;
     return os.str();
   }
+
+  std::string __repr__()
+  {
+    std::ostringstream os;
+    os << *self;
+    return os.str();
+  }
 }
 
 %extend spot::twa_run {

wrap/python/tests/Makefile.am

@@ -31,6 +31,7 @@ LOG_DRIVER = $(TEST_LOG_DRIVER)
 check_SCRIPTS = run
 
 TESTS = \
+  acc_cond.ipynb \
   accparse.ipynb \
   accparse2.py \
   alarm.py \