rewrite the stdio module to be less broken. also add sehbang support

examples/number_array.csn

@@ -3,6 +3,6 @@
     (sym buf r7)
     (mkbf buf (r0 66 67 68 '\n'))
 
-    (bfrpop @stdout @buf)
+    (bfrpop @cout @buf)
     (s.nem -1)
 )

examples/stdio.csn

@@ -20,27 +20,27 @@
         (:next)
             (bfrd ch @str pos)
             (ret.ov)
-            (ld @stdout ch)
+            (ld @cout ch)
             (inc pos)
         (j :next)
     )
 
     (:loop)
-        (ld r0 @stdin)
+        (ld r0 @cin)
 
         (cmp r0 'q'
-            (eq? (ld @stdout '\n')
+            (eq? (ld @cout '\n')
                  (halt)))
 
         ; uppercase ASCII
         (cmp r0 'a' (<? (j :badchar)))
         (cmp r0 'z' (>? (j :badchar)))
         (sub r0 ' ')
-        (ld @stdout r0)
+        (ld @cout r0)
     (j :loop)
 
     (:badchar)
-        (ld @stdout r0)
+        (ld @cout r0)
         (bfrd r0 @TXT T_UNK)
         (call print r0)
     (j :loop)

examples/stdio_rev.csn

@@ -1,9 +1,9 @@
 (
     (mkbf r7)
-    (:r)(ld r0 @stdin)
+    (:r)(ld r0 @cin)
         (cmp r0 '\n' (eq? (j :q)))
         (bfpush @r7 r0)
         (j :r)
-    (:q)(bfpop @stdout @r7 (nem? (j :q)))
-    (ld @stdout '\n')
+    (:q)(bfpop @cout @r7 (nem? (j :q)))
+    (ld @cout '\n')
 )

examples/stdio_rot13.csn

@@ -1,6 +1,9 @@
+#!/usr/bin/env crsn
 (
     (:again)
-    (ld r0 @stdin (inval? (halt)))
+    (ld r0 @cin
+        (eof? (halt))
+        (inval? (j :again)))
     (rcmp r0 'A' 'Z'
         (eq? (ld r1 'A'))
         (ne? (rcmp r0 'a' 'z'
@@ -11,6 +14,6 @@
     (mod r0 26)
     (add r0 r1)
     (:print)
-    (ld @stdout r0)
+    (ld @cout r0)
     (j :again)
 )