Create some kind of Equalable trait

[dkettlestrings]

Due to the JVM's insistence that everything has an equals method that

1. Is invoked by many standard operations (especially standard collections)
2. Has a signature that requires it handle Any

we have ugly code. Take for example this snippet from Polynomial:

override def equals(obj: scala.Any): Boolean = {

    Try(obj.asInstanceOf[Polynomial[A]]) match {
      case Success(poly) => this.param == poly.param && trimLeadingZeros(this.coefficients) == trimLeadingZeros(poly.coefficients)
      case Failure(throwable) => false
    }
  }

The asInstanceOf guard is ugly and gets repeated anywhere I want to have a specific notion of equality. As of the writing of this issue, it appears in

1. Polynomial
2. ResidueClass
3. RationalExpression

Create a trait that handles the type guard and allows the user to simply write the actual equality logic on the appropriate type.

[dkettlestrings]

This turns out to be much harder than I thought. In fact, Martin Odersky is proposing such a thing for Dotty. I'll just have to leave this open and see what happens. I'm concerned with moving to Dotty as most people aren't using it (I think).

[dkettlestrings]

Easier than I thought. Pushing a change now.