Add support for the Lepcha script (bug#55869)

* lisp/language/indian.el ("Lepcha"): New language environment.
Add composition rules for Lepcha. Add sample text and input method.
* lisp/language/misc-lang.el ("Kharoshthi"): Fix whitespace.
* lisp/international/fontset.el (script-representative-chars)
(setup-default-fontset): Support Lepcha.
* lisp/leim/quail/indian.el ("lepcha"): New input method.

* etc/HELLO: Add a Lepcha greeting.
* etc/NEWS: Announce the new language environment.

lisp/language/indian.el

@@ -244,6 +244,17 @@ Languages such as Sanskrit and Manipravalam, when they use the
 Grantha script, are supported in this language environment."))
  '("Indian"))
 
+(set-language-info-alist
+ "Lepcha" '((charset unicode)
+            (coding-system utf-8)
+            (coding-priority utf-8)
+            (input-method . "lepcha")
+            (sample-text . "Lepcha (ᰛᰩᰵ)	ᰂᰦᰕᰥᰬ")
+            (documentation . "\
+Lepcha language and its script are supported in this
+language environment."))
+ '("Indian"))
+
 ;; Replace mnemonic characters in REGEXP according to TABLE.  TABLE is
 ;; an alist of (MNEMONIC-STRING . REPLACEMENT-STRING).
 
@@ -734,5 +745,19 @@ Grantha script, are supported in this language environment."))
                                        "?" avagraha "?")
                                1 'font-shape-gstring))))
 
+;; Lepcha composition rules
+(let ((consonant            "[\x1C00-\x1C23\x1C4D-\x1C4F]")
+      (vowel                "[\x1C26-\x1C2C]")
+      (subjoined-letter     "[\x1C24\x1C25]")
+      (consonant-sign       "[\x1C2D-\x1C35]")
+      (other-signs          "[\x1C36\x1C37]"))
+  (set-char-table-range composition-function-table
+                        '(#x1C24 . #x1C37)
+                        (list (vector
+                               ;; Consonant based syllables
+                               (concat consonant other-signs "?" vowel "?"
+                                       consonant-sign "?" subjoined-letter "?")
+                               1 'font-shape-gstring))))
+
 (provide 'indian)
 ;;; indian.el ends here

lisp/language/misc-lang.el

@@ -242,11 +242,11 @@ in this language environment.")))
 
 (set-language-info-alist
  "Kharoshthi" '((charset unicode)
-	           (coding-system utf-8)
-	           (coding-priority utf-8)
-	           (input-method . "kharoshthi")
-               (sample-text . "Kharoṣṭhī (𐨑𐨪𐨆𐨛𐨁)	𐨣𐨨𐨲𐨪𐨆 𐨐𐨪𐨅𐨨𐨁")
-	           (documentation . "\
+	        (coding-system utf-8)
+	        (coding-priority utf-8)
+	        (input-method . "kharoshthi")
+                (sample-text . "Kharoṣṭhī (𐨑𐨪𐨆𐨛𐨁)	𐨣𐨨𐨲𐨪𐨆 𐨐𐨪𐨅𐨨𐨁")
+	        (documentation . "\
 Language environment for Gāndhārī, Sanskrit, and other languages
 using the Kharoṣṭhī script.")))
 
@@ -255,7 +255,7 @@ using the Kharoṣṭhī script.")))
       (virama        "\U00010A3F")
       (modifier      "[\U00010A0C-\U00010A0F\U00010A38-\U00010A3A]"))
   (set-char-table-range composition-function-table
-		                '(#x10A3F . #x10A3F)
+		        '(#x10A3F . #x10A3F)
                         (list
                          (vector
                           (concat consonant