Espruino 32 bit int switch

@DrAzzy, you're probably best off using a Uint8Array and wasting 7 out of the 8 bits.

@Stev, not at the moment I'm afraid. It could be an idea though. Someone could make a module based on Java's BigInteger class that used Uint32Array for the data. It should be relatively speedy for simple operations.

I'd wanted to make a UintNArray class that would use arbitrarily-sized integers - for instance I know 1 bit, 4 bit, and 24 bit would be handy. A Uint64Array wouldn't be much use because there'd be no way to get data in or out of it though :(