Global thread pool is now a thread pool executor.
Added at_exit hook to shutdown the global thread pool.
Added second global thread pool for long-running tasks.
Added #at_exit hooks to Java thread pools.
Future and Async now support explicit executor options.
Agent now uses executor option instead of UsesGlobalThreadPool.
Minor documentation updates to Future.
Minor documentation updates to Agent.
Promise now uses :executor option instead of UsesGlobalThreadPool.
Completely deprecated UsesGlobalThreadPool in lieu of :executor option.
Merge branch 'master' into global-thread-pool
Minor thread pool spec refactoring.
Renamed method for better readability.
Fixed dataflow (broken when executor option added to Future)
Async now uses global thread pool.
Longer timeouts in Exchanger spec.
Better global thread pool configuration during tests.
Fixed typo in dataflow spec.
Merge pull request #42 from jdantonio/global-thread-pool

Global thread pool is now a thread pool executor.
Added Concurrent::dataflow_with for explicitly setting the executor.