adjust to Swig 4.1.0

* python/spot/__init__.py: Add flatnested versions of some static
methods.
* spot/twa/acc.hh: Hide && version of & and |, causing trouble
to swig.
* tests/python/_synthesis.ipynb, tests/python/synthesis.ipynb:
Upgrade expected type names.
* tests/python/ipnbdoctest.py: Adjust for difference between 4.0 and
4.1.

spot/twa/acc.hh

@@ -1011,6 +1011,7 @@ namespace spot
         return res;
       }
 
+#ifndef SWIG
       /// \brief Conjunct the current condition with \a r.
       acc_code operator&(acc_code&& r) const
       {
@@ -1018,6 +1019,7 @@ namespace spot
         res &= r;
         return res;
       }
+#endif // SWIG
 
       /// \brief Disjunct the current condition in place with \a r.
       acc_code& operator|=(const acc_code& r)
@@ -1106,6 +1108,7 @@ namespace spot
         return *this;
       }
 
+#ifndef SWIG
       /// \brief Disjunct the current condition with \a r.
       acc_code operator|(acc_code&& r) const
       {
@@ -1113,6 +1116,7 @@ namespace spot
         res |= r;
         return res;
       }
+#endif // SWIG
 
       /// \brief Disjunct the current condition with \a r.
       acc_code operator|(const acc_code& r) const