p8: fixed issue with p8 not following ANSI C standard

lib/io.c

@@ -0,0 +1,24 @@
+
+#include "io.h"
+
+int readnum(FILE *fd, char *buf, size_t len) {
+
+    int i = 0;
+
+    for(;;) {
+        int c = getc(fd);
+        
+        if (c == EOF)
+            break;
+        if (c < '0' || c > '9')
+            continue;
+            
+        buf[i] = c;
+        
+        if (i+1 > len)
+            break;
+        i++;
+    }
+
+    return i;
+}

lib/io.h

@@ -0,0 +1,9 @@
+
+#ifndef __IO_H
+#define __IO_H
+
+#include <stdio.h>
+
+int readnum(FILE *fd, char *buf, size_t len);
+
+#endif /* __IO_H */