optimize filename normalize (org-roam#1460)

* Normalize slug using ucs-normalize-NFC-string after remove Unicode spacing mark
* Add org-roam-slug--preserve-chars-from-normalization for Unicode Normalization
* Add org-roam-slug-trim-chars instead of org-roam-slug--preserve-chars-from-normalization

org-roam.el

@@ -234,6 +234,35 @@ Function should return a filename string based on title."
   :type 'function
   :group 'org-roam)
 
+(defcustom org-roam-slug-trim-chars
+  '(;; Combining Diacritical Marks https://www.unicode.org/charts/PDF/U0300.pdf
+    768 ; U+0300 COMBINING GRAVE ACCENT
+    769 ; U+0301 COMBINING ACUTE ACCENT
+    770 ; U+0302 COMBINING CIRCUMFLEX ACCENT
+    771 ; U+0303 COMBINING TILDE
+    772 ; U+0304 COMBINING MACRON
+    774 ; U+0306 COMBINING BREVE
+    775 ; U+0307 COMBINING DOT ABOVE
+    776 ; U+0308 COMBINING DIAERESIS
+    777 ; U+0309 COMBINING HOOK ABOVE
+    778 ; U+030A COMBINING RING ABOVE
+    780 ; U+030C COMBINING CARON
+    795 ; U+031B COMBINING HORN
+    803 ; U+0323 COMBINING DOT BELOW
+    804 ; U+0324 COMBINING DIAERESIS BELOW
+    805 ; U+0325 COMBINING RING BELOW
+    807 ; U+0327 COMBINING CEDILLA
+    813 ; U+032D COMBINING CIRCUMFLEX ACCENT BELOW
+    814 ; U+032E COMBINING BREVE BELOW
+    816 ; U+0330 COMBINING TILDE BELOW
+    817 ; U+0331 COMBINING MACRON BELOW
+    )
+  "Characters to trim from Unicode normalization for slug.
+
+By default, the characters are specified to remove Diacritical Marks from the Latin alphabet."
+  :type '(repeat character)
+  :group 'org-roam)
+
 (defcustom org-roam-title-sources '((title headline) alias)
   "The list of sources from which to retrieve a note title.
 Each element in the list is either:
@@ -794,10 +823,11 @@ Each ref is returned as a cons of its type and its key."
 (defun org-roam--title-to-slug (title)
   "Convert TITLE to a filename-suitable slug."
   (cl-flet* ((nonspacing-mark-p (char)
-                                (eq 'Mn (get-char-code-property char 'general-category)))
+                                (memq char org-roam-slug-trim-chars))
              (strip-nonspacing-marks (s)
-                                     (apply #'string (seq-remove #'nonspacing-mark-p
-                                                                 (ucs-normalize-NFD-string s))))
+                                     (ucs-normalize-NFC-string
+                                      (apply #'string (seq-remove #'nonspacing-mark-p
+                                                                  (ucs-normalize-NFD-string s)))))
              (cl-replace (title pair)
                          (replace-regexp-in-string (car pair) (cdr pair) title)))
     (let* ((pairs `(("[^[:alnum:][:digit:]]" . "_")  ;; convert anything not alphanumeric