initial reformatting of comments for Doxygen

hypgraph.cpp

@@ -1,5 +1,9 @@
 // Hyperbolic Rogue -- hyperbolic graphics
-// Copyright (C) 2011-2018 Zeno Rogue, see 'hyper.cpp' for details
+// Copyright (C) 2011-2019 Zeno Rogue, see 'hyper.cpp' for details
+
+/** \file hypgraph.cpp
+ *  \brief mapping hyperpoints to the screen, and related functions
+ */
 
 namespace hr {