Refactor enmasse() and recurse() to reflect depth

The HLP-changes to sbase have been a great addition of functionality,
but they kind of "polluted" the enmasse() and recurse() prototypes.
As this will come in handy in the future, knowing at which "depth"
you are inside a recursing function is an important functionality.

Instead of having a special HLP-flag passed to enmasse, each sub-
function needs to provide it on its own and can calculate results
based on the current depth (for instance, 'H' implies 'P' at
depth > 0).
A special case is recurse(), because it actually depends on the
follow-type. A new flag "recurse_follow" brings consistency into
what used to be spread across different naming conventions (fflag,
HLP_flag, ...).

This also fixes numerous bugs with the behaviour of HLP in the
tools using it.

cp.c

@@ -51,7 +51,7 @@ main(int argc, char *argv[])
 		if (!S_ISDIR(st.st_mode))
 			eprintf("%s: not a directory\n", argv[argc - 1]);
 	}
-	enmasse(argc, argv, cp, cp_HLPflag);
+	enmasse(argc, argv, cp);
 
 	return cp_status;
 }