Fix various mismatched prototypes and other compilation problems.

Core (make cpc) builds again, but crashes on startup.
diff --git a/contiki-cpc/ctk/conio.h b/contiki-cpc/ctk/conio.h
index e8c3cdb..859e905 100644
--- a/contiki-cpc/ctk/conio.h
+++ b/contiki-cpc/ctk/conio.h
@@ -40,7 +40,7 @@
 
 char cgetc (void);
 
-void  revers ();
+void  revers (char);
 
 void textcolor (unsigned char color);