Fix: floating point precision

[sitch]

Currently this uses floats to perform arithmetic, which leads to unexpected evals over certain numerical intersections

This test currently passes, but most people's general conceptions would expect this to fail

    test "floating point arithmetic" do
      refute JsonLogic.apply(%{"+" => [0.1, 0.2]}) == 0.3
      assert JsonLogic.apply(%{"+" => [0.1, 0.2]}) == 0.30000000000000004
    end

[sitch]

I tried to put this in to fix it but there are some guards clauses that break, so it'll need to have individual methods looked at:

  import Kernel,
    except: [
      {:+, 2},
      {:-, 2},
      {:/, 2},
      {:*, 2},
      {:==, 2},
      {:!=, 2},
      {:>, 2},
      {:<, 2},
      {:>=, 2},
      {:<=, 2}
    ]

  def x + y do
    x |> Decimal.add(y) |> Decimal.to_float()
  end

  def x - y do
    x |> Decimal.sub(y) |> Decimal.to_float()
  end

  def x * y do
    x |> Decimal.mult(y) |> Decimal.to_float()
  end

  def x / y do
    x |> Decimal.div(y) |> Decimal.to_float()
  end

  def x == y do
    Decimal.equals?(x, y)
  end

  def x != y do
    not Decimal.equals?(x, y)
  end

  def x >= y do
    Decimal.gt?(x, y) or Decimal.equals?(x, y)
  end

  def x <= y do
    Decimal.lt?(x, y) or Decimal.equals?(x, y)
  end

  def x > y do
    Decimal.gt?(x, y)
  end

  def x < y do
    Decimal.lt?(x, y)
  end

[axelson]

Although on the other hand it does match the javascript version: