Add pmapallv utility function

src/propeller/utils.cljc

@@ -85,3 +85,22 @@
                  zip/path
                  count
                  (max height))))))
+
+(defn pmapallv
+  "A utility for concurrent execution of a function on items in a collection.
+In single-thread-mode this acts like mapv. Otherwise it acts like pmap but: 
+1) coll should be finite, 2) the returned sequence will not be lazy, and will
+in fact be a vector, 3) calls to f may occur in any order, to maximize
+multicore processor utilization, and 4) takes only one coll so far."
+  [f coll args]
+  #?(:clj (vec (if (:single-thread-mode args)
+                 (doall (map f coll))
+                 (let [agents (map #(agent % :error-handler
+                                           (fn [agnt except] 
+                                             (clojure.repl/pst except 1000) 
+                                             (System/exit 0)))
+                                   coll)]
+                   (dorun (map #(send % f) agents))
+                   (apply await agents)
+                   (doall (map deref agents)))))
+     :cljs (mapv f coll)))