* Use maps, instead of tuples, for many callback module arguments

* Start brokers/regulators using sys.config
* Add rate limit valve
* Add dirty_* async functions as equivalent to sync
* Add default infinity timeout to many calls that required timeout
* Fix exit reasons for sbroker/sregulator

* Reset allowance in pie meter to correct value

Fix pie allowance calculation

* Fix incorrect bound on open time in regulator

* Allow async_ask(_r) for other processes

* Improve relative time values

* Always use erlang:monotonic_time/0

* Always use `milli_seconds` for configuration
* Add minimum queue size for actively managed queues
* Allow callbacks to control timeouts
* Add `sbroker_fair_queue` for fair queuing on brokers
* Return monitor from queues and try to prevent returning dead pid
* Add meters (with `sbroker_meter`)
* Introduce `sprotector` and `sprotector_pie_meter` for short circuit
* Introduce `sbetter` and `srand` for load balancing brokers
* Add `sbroker:dynamic_ask(_r)/1,2`
* Add `sregulator` for pool resizing

Control timeout with queue instead of fixed timeout

Fix elixir support

Fix sbroker timer

* Use erlang:monotonitc_time/0 and erlang:now/0 to read time

* Add RelativeTime to go tuples to mleasure queue imbalance
* Change sregulator:update to be synchronous and new arguments
* Add InTime to squeue/svalve to insert items in the past
* Add OutTime/DropTime to svalve to react to signals in the past
* Allow negative times in queues
* Document squeue and svalve behaviours