Cleanup: reorganize doxygen modules

- Nest compositor pages under the compositor module
- Nest GUI, DNA/RNA & externformats modules under Blender.
- Remove modules from intern which no longer exist.
- Add intern modules (atomic, eigen, glew-mx, libc_compat, locale,
  numaapi, rigidbody, sky, utfconv).
- Use 'intern_' prefix for intern modules since some of the modules
  use generic terms such as locale & atomic.

intern/utfconv/utf_winfunc.c

@@ -17,6 +17,10 @@
  * All rights reserved.
  */
 
+/** \file
+ * \ingroup intern_utf_conv
+ */
+
 #ifndef _WIN32_IE
 #  define _WIN32_IE 0x0501
 #endif

intern/utfconv/utf_winfunc.h

@@ -15,7 +15,10 @@
  *
  * The Original Code is Copyright (C) 2012 Blender Foundation.
  * All rights reserved.
- *
+ */
+
+/** \file
+ * \ingroup intern_utf_conv
  */
 
 #ifndef __UTF_WINFUNC_H__

intern/utfconv/utfconv.c

@@ -15,7 +15,10 @@
  *
  * The Original Code is Copyright (C) 2012 Blender Foundation.
  * All rights reserved.
- *
+ */
+
+/** \file
+ * \ingroup intern_utf_conv
  */
 
 #include "utfconv.h"

intern/utfconv/utfconv.h

@@ -15,7 +15,10 @@
  *
  * The Original Code is Copyright (C) 2012 Blender Foundation.
  * All rights reserved.
- *
+ */
+
+/** \file
+ * \ingroup intern_utf_conv
  */
 
 #ifndef __UTFCONV_H__