to_parity: improve doc, and rename car_option into to_parity_options

* spot/twaalgos/toparity.hh: Improve doc, and rename car_option into
to_parity_options.
* doc/spot.bib: Add one reference.
* python/spot/__init__.py, spot/twaalgos/toparity.cc,
tests/python/toparity.py: Adjust.

doc/spot.bib

@@ -425,6 +425,23 @@
   pages		= {51--61}
 }
 
+@InProceedings{	  kretinsky.17.tacas,
+  author	= {Jan K\v{r}et{\'{\i}}nsk{\'{y}} and Tobias Meggendorfer and
+		  Clara Waldmann and Maximilian Weininger},
+  editor	= {Axel Legay and Tiziana Margaria},
+  title		= {Index Appearance Record for Transforming {R}abin Automata
+		  into Parity Automata},
+  booktitle	= {Proceedings of the 23st International Conference on Tools
+		  and Algorithms for the Construction and Analysis of Systems
+		  (TACAS'17)},
+  part		= {I},
+  series	= {Lecture Notes in Computer Science},
+  volume	= {10205},
+  pages		= {443--460},
+  year		= {2017},
+  doi		= {10.1007/978-3-662-54577-5_26}
+}
+
 @InProceedings{	  kretisnky.12.cav,
   author	= {Jan K{\v{r}}et{\'i}nsk{\'y} and Javier Esparza},
   title		= {Deterministic Automata for the {(F,G)}-Fragment of {LTL}},