CLEANUP: assorted typo fixes in the code and comments

These are mostly comments in the code. A few error messages were fixed
and are of low enough importance not to deserve a backport. Some regtests
were also fixed.
diff --git a/include/common/xref.h b/include/common/xref.h
index f7fe26d..610a023 100644
--- a/include/common/xref.h
+++ b/include/common/xref.h
@@ -46,7 +46,7 @@
 		if (local == XREF_BUSY)
 			continue;
 
-		/* We are locked, the peer cant disapear, try to acquire
+		/* We are locked, the peer can't disappear, try to acquire
 		 * the pper's lock. Note that remote can't be NULL.
 		 */
 		remote = _HA_ATOMIC_XCHG(&local->peer, XREF_BUSY);