Adding egrep hook; better iteration for whitespace; improving local tests

Hooks/scripts.d/egrep

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+if git ls-files | xargs --delimiter='\n' grep -irlE 'egrep' | grep -v 'Hooks/scripts.d/egrep' ; then
+    echo 'Egrep has been deprecated as of GNU grep 3.8 -- replace `egrep` with `grep -E`.'
+    echo https://www.gnu.org/software/grep/manual/grep.html
+    exit 1
+fi