feature: profiling / timing

[talss89]

It makes sense to me that developers will need to perf check any hooks they monkey-patch in some way.

It would be nice to include a basic API for this. Perhaps something like:

define('GORILLA_PROFILE', true);

/* Do something with hooks */

gorillaclaw_perf_report();

Feature criteria:

• Need: Minimal performance impact
• Need: No performance impact when disabled (default)
• Want: Some kind of machine readable output, so we can integrate with CI pipelines