Add escaped single and double quotes

bootstrap.fs

@@ -1177,6 +1177,8 @@ decimal \ set default to decimal
     'v' of 11 endof
     'f' of 12 endof
     'r' of 13 endof
+    [char] ' of [char] ' endof
+    [char] " of [char] " endof
     '\\' of '\\' endof
     drop -1
     endcase

test/core.fs

@@ -614,6 +614,9 @@ T{ char HELLO -> 48 }T
 T{ '\n' -> 0xa }T
 T{ '\0' -> 0 }T
 T{ 'a' -> 61 }T
+T{ '"' -> 22 }T
+T{ '\"' -> 22 }T
+T{ '\'' -> 27 }T
 T{ : gc1 [char] X ; -> }T
 T{ : gc2 [char] HELLO ; -> }T
 T{ gc1 -> 58 }T