Upgrade RNG

Battle.prototype.random now uses the LCRNG for Gen 5
Battle.prototype.nextFrame calculates what the seed will be next turn or
next n turns.
Force words unsigned

Make sure values in words remained unsigned integers
Add missing bracket
Implement a faster and generalised Gen 5 LCRNG
Merge pull request #270 from kotarou3/bwrng

Use Gen 5 RNG - Improved