Adding an annotation to set prover arguments per method

[marcoeilers]

Adding an annotation @proverArgs(key=value) to set prover configuration parameters per method.

Example usage:

@proverArgs("smt.arith.nl=false")
method m2(i: Int, i2: Int)
    requires i >= 0
    requires i2 >= 0
{
    //:: ExpectedOutput(assert.failed:assertion.false)
    assert i * i2 >= 0
}

[jcp19]

Seems good to me