Add optional term argument to hints

[andrew-johnson-4]

Is your feature request related to a problem? Please describe.
Hints may need to be parameterized to prove a goal. This parameter should be a single term so that hints can nest inside of other hints.

Describe the solution you'd like

//axioms
axiom @reflexive a. [True] = a == a;
axiom @symmetric a, b. [True] = a == b => b == a;
axiom @transitive a, b, c. [True] = a == b && b == c => a == c;
x == z @transitive(x == y && y == z)