More test cases for ->/2
More test cases for ->/2

These cases, like all the others, are derived from the ISO Standard
and from Prolog: The Standard by Deransart, etal.

Before committing, I intentionally broke ->/2 and made all tests fail.
I then restored the correct implementation and they all passed: red
light, green light.

samuell/golog,mndrix/golog,vzaramel/golog,samuell/golog,bransorem/golog,bransorem/golog,vzaramel/golog,mndrix/golog