Revert "create set of fixed slots based off of numprocesses"

This reverts commit aea929e7e6ca679b09d8fe4e0e2af08a747bc6d5.
supply a worker id that tracks w/ numprocesses

worker id's are reused as their corresponding process is reaped
a new property is added: "Watcher.nextwid" which returns the lowest unused worker id number