XML encode # character in SVGs

Fixes #130.

See also https://stackoverflow.com/a/38459219.

src/day8/re_frame/trace/utils/macros.clj

@@ -1,10 +1,18 @@
 (ns day8.re-frame.trace.utils.macros
-  (:require [clojure.java.io :as io]))
+  (:require [clojure.java.io :as io]
+            [clojure.string :as str]))
 
 (defmacro slurp-macro
-  "Reads a file as a string. Slurp is wrapped in a macro so it can interact with local files before clojurescript compilation."
+  "Reads a file as a string. Slurp is wrapped in a macro so it can interact with local files before clojurescript compilation.
+  #'s are replaced with %23 for URL encoding."
+  ;; For reasons unknown (to me), browsers don't like URL encoding the entire string.
+  ;; I suspect XML encoding the attributes is the correct way to do this, but
+  ;; #'s are the problem here, so we so we do surgery on the one problematic symbol.
   [path]
-  (slurp (io/resource path)))
+  (str/replace
+    (slurp (io/resource path))
+    "#"
+    "%23"))
 
 (defmacro with-cljs-devtools-prefs [prefs & body]
   `(let [previous-config# (devtools.prefs/get-prefs)