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/runtime/function-slot.scm

@@ -56,7 +56,7 @@
                  (compile-function . function)
                  (compile-defun . defun)
                  (compile-defmacro . defmacro)
-                 (compile-\` . \`)
+                 (#{compile-`}# . #{`}#)
                  (compile-quote . quote)))
   #:duplicates (last)
   ;; special operators
@@ -79,7 +79,7 @@
                function
                defun
                defmacro
-               \`
+               #{`}#
                quote)
   ;; macros
   #:re-export (lambda