New checks:

• PressureAverage which checks Linux Pressure Stall Information (PSI) for CPU, I/O, and memory.
• ProcessExitStatus which runs a process and checks its exit status code. This gives a lot of flexibility to implement custom checks.

Incompatible changes

• The default value for "memory" in the MemoryUsage check config was changed from true to false (see #18).
• The placeholder alarm_id has been renamed to check_id for more consistent naming.

And some minor fixes and changes.

Happy holidays!