Profiling spy.

Use this macro to wrap forms that should be timed during active profiling.
A unique form id (keyword) must be provided, e.g.:

  (p      ::my-form  (do-something))
  (p {:id ::my-form} (do-something))
  (p {:id ::my-form
      :level :debug} (do-something))

`p` will ALWAYS execute its body and return the body's result, even when
profiling isn't active.

Options include:
  `:id` ---- Unique id for this form in resulting `pstats` (e.g. `::my-fn-call`)
  `:level` - Profiling level ∈ #{<int> :trace :debug :info :warn :error :fatal :report ...}
             (default `:info`)
