Improve crash when interpreter fails to increment

JavaScript's [Number type](http://www.ecma-international.org/ecma-262/5.1/#sec-8.5) can only represent integers up to 2^53. When the Nock interpreter attempts to increment (with Nock operator 4) an atom equal to 2^53, it will result in the same atom, which violates the Nock specification. The interpreter will detect a loop and crash, but there are two problems: (1) it's not crashing for the right reason, and (2) it doesn't give helpful information about what went wrong. This modifies the interpreter to check for this case and throw an error.