Bugfix and adding features.

*Fixed an issue with generating random strings.
*Stacks may now push a range of objects without the coder having to iterate the collection manually.
*Stopwatches now compute elapsed micro and nanoseconds for convenience.
*Added BlockCopy() extension methods for streams to copy chunks or data similar to the CopyTo() method.
*Add crypto providers for ROT13 and Atbash ciphers.