some printing improvements

- don't print shared references to cprims, and estimate their
  size better. previously you could get output like this:

```
(#0=#\a
 #0#)
```

Now it looks like:

```
(#\a #\a)
```

- print `#\ ` and `#\newline` instead of `#\space` and `#\linefeed`.
  these seem to be more standard.

print.c

@@ -89,9 +89,6 @@ void print_traverse(value_t v)
         for(i=0; i < vector_size(v); i++)
             print_traverse(vector_elt(v,i));
     }
-    else if (iscprim(v)) {
-        mark_cons(v);
-    }
     else if (isclosure(v)) {
         mark_cons(v);
         function_t *f = (function_t*)ptr(v);
@@ -171,7 +168,7 @@ static inline int tinyp(value_t v)
     if (fl_isstring(v))
         return (cv_len((cvalue_t*)ptr(v)) < SMALL_STR_LEN);
     return (isfixnum(v) || isbuiltin(v) || v==FL_F || v==FL_T || v==FL_NIL ||
-            v == FL_EOF);
+            v == FL_EOF || iscprim(v));
 }
 
 static int smallp(value_t v)
@@ -208,6 +205,8 @@ static int lengthestimate(value_t v)
     // get the width of an expression if we can do so cheaply
     if (issymbol(v))
         return u8_strwidth(symbol_name(v));
+    if (iscprim(v) && cp_class((cprim_t*)ptr(v)) == wchartype)
+        return 4;
     return -1;
 }
 
@@ -441,9 +440,13 @@ void fl_print_child(ios_t *f, value_t v)
             }
         }
         break;
-    case TAG_CVALUE:
     case TAG_CPRIM:
-        if (v == UNBOUND) { outs("#<undefined>", f); break; }
+        if (v == UNBOUND)
+            outs("#<undefined>", f);
+        else
+            cvalue_print(f, v);
+        break;
+    case TAG_CVALUE:
     case TAG_VECTOR:
     case TAG_CONS:
         if (print_circle_prefix(f, v)) break;
@@ -477,7 +480,7 @@ void fl_print_child(ios_t *f, value_t v)
             outc(']', f);
             break;
         }
-        if (iscvalue(v) || iscprim(v))
+        if (iscvalue(v))
             cvalue_print(f, v);
         else
             print_pair(f, v);
@@ -640,13 +643,13 @@ static void cvalue_printdata(ios_t *f, void *data, size_t len, value_t type,
             else if (wc == 0x07) outsn("alarm", f, 5);
             else if (wc == 0x08) outsn("backspace", f, 9);
             else if (wc == 0x09) outsn("tab", f, 3);
-            else if (wc == 0x0A) outsn("linefeed", f, 8);
+            //else if (wc == 0x0A) outsn("linefeed", f, 8);
-            //else if (wc == 0x0A) outsn("newline", f, 7);
+            else if (wc == 0x0A) outsn("newline", f, 7);
             else if (wc == 0x0B) outsn("vtab", f, 4);
             else if (wc == 0x0C) outsn("page", f, 4);
             else if (wc == 0x0D) outsn("return", f, 6);
             else if (wc == 0x1B) outsn("esc", f, 3);
-            else if (wc == 0x20) outsn("space", f, 5);
+            //else if (wc == 0x20) outsn("space", f, 5);
             else if (wc == 0x7F) outsn("delete", f, 6);
             else if (iswprint(wc)) outs(seq, f);
             else HPOS+=ios_printf(f, "x%04x", (int)wc);

string.c

@@ -230,7 +230,7 @@ value_t fl_char_upcase(value_t *args, u_int32_t nargs)
     argcount("char.upcase", nargs, 1);
     cprim_t *cp = (cprim_t*)ptr(args[0]);
     if (!iscprim(args[0]) || cp_class(cp) != wchartype)
-      type_error("char.upcase", "wchar", args[0]);
+        type_error("char.upcase", "wchar", args[0]);
     return mk_wchar(towupper(*(int32_t*)cp_data(cp)));
 }
 value_t fl_char_downcase(value_t *args, u_int32_t nargs)
@@ -238,7 +238,7 @@ value_t fl_char_downcase(value_t *args, u_int32_t nargs)
     argcount("char.downcase", nargs, 1);
     cprim_t *cp = (cprim_t*)ptr(args[0]);
     if (!iscprim(args[0]) || cp_class(cp) != wchartype)
-      type_error("char.downcase", "wchar", args[0]);
+        type_error("char.downcase", "wchar", args[0]);
     return mk_wchar(towlower(*(int32_t*)cp_data(cp)));
 }