[boost] cycle_iterator update

Here is an update to cycle_iterator. This is based on the original design by Gennadiy Rozental. After fairly extensive performance testing I am getting good results (compared to my old implementation which was hand-written, not based on boost iterators), after adding operator[]. There are two versions, both give about the same performance in my tests. One version, which I prefer, modifies the underlying base iterator for operations such as increment. The other implementation never touches the base iterator, but modifies an integral offset value. Also included is a Ring container adaptor class, which adapts a container (e.g., std::vector) to a ring. Basic operations are there, but more can be added. Also a simple test program.