CLEANUP: assorted typo fixes in the code and comments

This is sixth iteration of typo fixes
diff --git a/src/stream_interface.c b/src/stream_interface.c
index 7bb864d..987fc01 100644
--- a/src/stream_interface.c
+++ b/src/stream_interface.c
@@ -1046,7 +1046,7 @@
 			cs->flags |= CS_FL_KILL_CONN;
 
 		if (si->flags & SI_FL_ERR) {
-			/* quick close, the socket is alredy shut anyway */
+			/* quick close, the socket is already shut anyway */
 		}
 		else if (si->flags & SI_FL_NOLINGER) {
 			/* unclean data-layer shutdown, typically an aborted request