use correct names for quasiquotation operators

Use #{`}#, #{,}# and #{,@}# as the quasiquote, unquote and
unquote-splicing operators, respectively. Previously they were named
escaping.

* module/language/elisp/compile-tree-il.scm (unquote?): Change "\," to
  "#{,}#".
  (unquote-splicing): Change "\,@" to "#{,@}#".
  (#{compile-`}#): Rename from #{compile-\`}#.
* module/language/elisp/runtime/function-slot.scm: Import #{compile-`}#
  instead of #{compile-\`}#, and re-export as #{`}# instead of as
  #{\`}#.
* module/language/elisp/parser.scm (quotation-symbols):
* test-suite/tests/elisp-compiler.test ("Eval", "Quotation"):
* test-suite/tests/elisp-reader.test ("Parser"): Change "\`", "\,", and
  "\,@" to "#{`}#", "#{,}#" and "#{,@}#", respectively.

module/language/elisp/compile-tree-il.scm

@@ -49,7 +49,7 @@
             compile-function
             compile-defmacro
             compile-defun
-            compile-\`
+            #{compile-`}#
             compile-quote))
 
 ;;; Certain common parameters (like the bindings data structure or
@@ -101,10 +101,10 @@
 ;;; unquote/unquote-splicing/backquote form.
 
 (define (unquote? sym)
-  (and (symbol? sym) (eq? sym '\,)))
+  (and (symbol? sym) (eq? sym '#{,}#)))
 
 (define (unquote-splicing? sym)
-  (and (symbol? sym) (eq? sym '\,@)))
+  (and (symbol? sym) (eq? sym '#{,@}#)))
 
 ;;; Build a call to a primitive procedure nicely.
 
@@ -876,7 +876,7 @@
                                                              body))
                               (make-const loc name)))))))
 
-(defspecial \` (loc args)
+(defspecial #{`}# (loc args)
   (pmatch args
     ((,val)
      (process-backquote loc val))))