matlabFunction is now a synonym of function_handle

This Fixes #154.  Rational for the name `function_handle`: this
is the class name for anonymous functions.  So its a bit like calling
double(sym(pi)).

I'd be happy to consider another names instead.
matlabFunction: simplify documentation

its in function_handle anyway.
Merge pull request #163 from cbm755/fcnhandle

Fcnhandle