setObjectDefaultOption("Reg")("reflect")(false);
setObjectDefaultOption("Reg")("labels")(false);
+def midpoint(expr a, b) = ((a + b) / 2) enddef;
+
\stopMPinclusions
+
+% Make \overrightarrow "unexpanded", to make it work within metapost.
+% http://www.ntg.nl/pipermail/ntg-context/2009/043620.html. Will be fixed in
+% context.
+\let\normaloverrightarrow\overrightarrow
+\unexpanded\def\overrightarrow{\normaloverrightarrow}