kernel: reader macros + 8 tests (Phase 1 closure) [consumes-lex]

Parser now reads 'expr, \`expr, ,expr, ,@expr as the four standard
shorthands. Quote uses existing $quote operative; quasiquote /
unquote / unquote-splicing recognised but not yet expanded at runtime
(left for first consumer to drive). 218 tests total across six suites.

lib/kernel/parser.sx

@@ -37,7 +37,10 @@
       (= c "(")
       (= c ")")
       (= c "\"")
-      (= c ";"))))
+      (= c ";")
+      (= c "'")
+      (= c "`")
+      (= c ","))))
 
 ;; Numeric grammar:  [+-]? (digit+ ('.' digit+)? | '.' digit+) ([eE][+-]?digit+)?
 (define
@@ -199,6 +202,16 @@
             ((= (at) "(") (do (adv) (read-list (list))))
             ((= (at) "\"")
               (do (adv) (kernel-string-make (read-string-body ""))))
+            ((= (at) "'")
+              (do (adv) (list "$quote" (read-form))))
+            ((= (at) "`")
+              (do (adv) (list "$quasiquote" (read-form))))
+            ((= (at) ",")
+              (do (adv)
+                  (cond
+                    ((= (at) "@")
+                      (do (adv) (list "$unquote-splicing" (read-form))))
+                    (:else (list "$unquote" (read-form))))))
             (:else (classify-atom (read-atom-body ""))))))
       (define
         read-list