create-peak-monitor now takes max-exceeded

max-exceeded is the number of sensors that need to exceed the threshold
before an alarm is raised.
Made create-peak-monitor generic

The functions that monitor the sensors are generic and don't need to be
a part of the protocol for starting/stopping the polling thread
Using At-At library to manage periodic polling
create-peak-monitor uses max-exceeded instead of hardcoding 2
ATATMonitor start uses a thread pool
ATATMonitors can be created with a polling function
wrap-atat-poll-fn saves state
Created place unimplemented sensor-loop function
Starting the AtAtMonitor calls the poll-function
The AtAtMonitor will call the poll-function multiple times