[2.3.x] + implement the task #1629
https://java.net/jira/browse/GRIZZLY-1629

"Extends IOStrategy API, so it can return the Executor for a specific event"
[2.3.x] add methods to ThreadCache, which accept currentThread parameter to avoid Thread.currentThread() call
[2.3.x] check flag status before CAS
[2.3.x] make SuspendStatus cacheable
[2.3.x] + implement the task #1630
https://java.net/jira/browse/GRIZZLY-1630

"Introduce CloseReason abstraction to provide information why Connection was closed"
[2.3.x] + fix copyright