Recognize non-ASCII escape sequences

As suggested in section 21.7.15 of the elisp manual, handle keyboard
events internally as vectors across the board, rather than preferring
strings when possible. This commit, in combination with the one before
it, fixes syl20bnr#51: `this-command-keys' returns a vector
for most key sequences, so (for instance) the expression

  (equal (this-command-keys) "π")

is always nil.

evil-escape.el

@@ -197,10 +197,12 @@ with a key sequence."
           (restore-buffer-modified-p modified)
           (cond
            ((and (characterp evt)
-                 (or (and (equal (this-command-keys) (evil-escape--first-key))
+                 (or (and (equal (this-command-keys-vector)
+                                 (evil-escape--first-key))
                           (char-equal evt skey))
                      (and evil-escape-unordered-key-sequence
-                          (equal (this-command-keys) (evil-escape--second-key))
+                          (equal (this-command-keys-vector)
+                                 (evil-escape--second-key))
                           (char-equal evt fkey))))
             (evil-repeat-stop)
             (let ((esc-fun (evil-escape-func)))
@@ -236,9 +238,9 @@ with a key sequence."
        (not (memq evil-state evil-escape-excluded-states))
        (or (not evil-escape-enable-only-for-major-modes)
            (memq major-mode evil-escape-enable-only-for-major-modes))
-       (or (equal (this-command-keys) (evil-escape--first-key))
+       (or (equal (this-command-keys-vector) (evil-escape--first-key))
            (and evil-escape-unordered-key-sequence
-                (equal (this-command-keys) (evil-escape--second-key))))
+                (equal (this-command-keys-vector) (evil-escape--second-key))))
        (not (cl-reduce (lambda (x y) (or x y))
                        (mapcar 'funcall evil-escape-inhibit-functions)
                        :initial-value nil))))
@@ -283,16 +285,14 @@ with a key sequence."
    (t 'evil-normal-state)))
 
 (defun evil-escape--first-key ()
-  "Return the first key string in the key sequence."
-  (let* ((first-key (elt evil-escape-key-sequence 0))
-         (fkeystr (char-to-string first-key)))
-    fkeystr))
+  "Return a vector containing just the first key in the key sequence."
+  (let ((first-key (elt evil-escape-key-sequence 0)))
+    (vector first-key)))
 
 (defun evil-escape--second-key ()
-  "Return the second key string in the key sequence."
-  (let* ((sec-key (elt evil-escape-key-sequence 1))
-         (fkeystr (char-to-string sec-key)))
-    fkeystr))
+  "Return a vector containing just the second key in the key sequence."
+  (let ((second-key (elt evil-escape-key-sequence 1)))
+    (vector second-key)))
 
 (defun evil-escape--insert-func ()
   "Default insert function."