Code Cleanup

- Renamed files task.h -> main.h, task.cpp -> main.cpp.  This is to
  prepare for the next rename, which addresses the OpenBSD bug.
- Removed utf8.h, utf8.cpp from Makefile.am, which were inadvertantly
  added.

src/interactive.cpp

@@ -32,7 +32,7 @@
 #include "Context.h"
 //#include "text.h"
 //#include "util.h"
-//#include "task.h"
+//#include "main.h"
 //#include "i18n.h"
 #include "../auto.h"