Implement standard arithmetic methods

[jngls]

We need all the standard arithmetic methods for dilated integers.

Citation [3] should be a useful reference for this.

• Determine which operators are suitable for dilated integers
• Implement operators
• Investigate options for Mul and Div

[jngls]

So far I've only been able to implement Add, AddAssign, Sub, SubAssign.

For multiplication, the answer is non-trivial. For example:

The value 3 D8 dilated is 0x101

0x101 * 0x101 = 0x10201 which is not a format compatible with a D8 dilated integer. The carry bits do not propagate through the integer in a dilated manner.

At the moment, I'm not sure there's a simple algebraic method to solve this. An algorithmic method would work, but I definitely want to avoid that.

[jngls]

Rather than creating a new issue for Mul and Div, I'm reopening this one.