add is_mex_fun()

Author: scivision

+stdlib/is_mex_fun.m

@@ -0,0 +1,5 @@
+%% IS_MEX_FUN detect if a function is loaded as MEX or plain .m
+
+function y = is_mex_fun(name)
+  y = endsWith(which(name), mexext());
+end