add first initial implementation of threadring
add first initial implementation of threadring

Threadring algorithm specification:
  http://benchmarksgame.alioth.debian.org/u32/performance.php?test=threadring#about

Test with 15 actors and 1,000,000 hops.

Current issues:
  When we use more than 15 actors the program crashes. It seems to be
  related to the GC detecting a cyclic structure and collecting the first
  agent.

parapluu/encore,parapluu/encore,parapluu/encore