Add error checking prototype

This is a prototype of how error checking could be made and reported. An
error "ArgumentError" has been created. It takes 4 arguments: the
function name, the exepcted type of an argument, the actual argument and
the 1-based index of the argument. From this it produces an error with a
nice message explaining which argument was incorrect.

Another module that has been created is a function "checkArgument". This
function is intended to be used in the other functions of ramda to
easilly check the type of all arguments.

Finally, an example of how to use this is implemented in pathEq. The
file produceError can be executed in node and is an example of correct
and incorrect usage of pathEq.

Since this is experimential so far, documentation and test are lacking
but will be included if we decide to go further with this.