This PR adds Merge() helper function for choosing which value of two pointers
to use during a larger merge operation.
If 'next' is not nil, use that value, otherwise use the 'previous' value.
This PR creates a pointer.Compare helper for comparing equality of
two pointers. Strictly only works with primitive types we know are
safe to derefence and compare using '=='.
This PR deprecates some functions in favor of generic alternatives.
The new functions are compatible only with Nomad v1.4+.
The old functions (nor their use) should not be removed until Nomad v1.6+.
