genem: cite our ATVA'19 paper

* doc/spot.bib (baier.19.atva): New reference.
* spot/twaalgos/genem.hh: Cite it.

doc/spot.bib

@@ -31,6 +31,23 @@
   doi		= {10.1007/978-3-642-39176-7_6}
 }
 
+@InProceedings{	  baier.19.atva,
+  author	= {Christel Baier and Franti\v{s}ek Blahoudek and Alexandre
+		  Duret-Lutz and Joachim Klein and David M\"uller and Jan
+		  Strej\v{c}ek},
+  title		= {Generic Emptiness Check for Fun and Profit},
+  booktitle	= {Proceedings of the 17th International Symposium on
+		  Automated Technology for Verification and Analysis
+		  (ATVA'19)},
+  year		= {2019},
+  volume	= {?????},
+  series	= {Lecture Notes in Computer Science},
+  pages		= {???--???},
+  month		= oct,
+  publisher	= {Springer},
+  note		= {To appear}
+}
+
 @InProceedings{	  beer.01.cav,
   author	= {Ilan Beer and Shoham Ben-David and Cindy Eisner and Dana
 		  Fisman and Anna Gringauze and Yoav Rodeh},