doxygen: unify use of \file across the board

Considering the various styles and implications found in the sources, edit
scores of files to follow the same API doc guidelines around the doxygen
grouping and the \file tag.

Many files now show a short description in the generated API doc that was so
far only available as C comment.

The guidelines and reasoning behind it is documented at
https://osmocom.org/projects/cellular-infrastructure/wiki/Guidelines_for_API_documentation

In some instances, remove file comments and add to the corresponding group
instead, to be shared among several files (e.g. bitvec).

Change-Id: Ifa70e77e90462b5eb2b0457c70fd25275910c72b
diff --git a/src/pseudotalloc/pseudotalloc.c b/src/pseudotalloc/pseudotalloc.c
index bc7a491..b77ffe9 100644
--- a/src/pseudotalloc/pseudotalloc.c
+++ b/src/pseudotalloc/pseudotalloc.c
@@ -1,7 +1,7 @@
-/* overly simplistic talloc replacement for deeply embedded
+/*! \file pseudotalloc.c
+ * overly simplistic talloc replacement for deeply embedded
  * microcontrollers.  Obviously this has none of the properties of real
- * talloc, it is particualrly not hierarchical at all */
-
+ * talloc, it is particualrly not hierarchical at all. */
 
 #include "talloc.h"
 #include <string.h>