patch 8.1.0857: indent functionality is not separated

Problem:    Ignore functionality is not separated.
Solution:   Move indent functionality into a new file. (Yegappan Lakshmanan,
            closes #3886)
diff --git a/Filelist b/Filelist
index 1eb9aa2..e053619 100644
--- a/Filelist
+++ b/Filelist
@@ -49,6 +49,7 @@
 		src/gui_beval.c \
 		src/hardcopy.c \
 		src/hashtab.c \
+		src/indent.c \
 		src/json.c \
 		src/json_test.c \
 		src/kword_test.c \
@@ -175,6 +176,7 @@
 		src/proto/gui_beval.pro \
 		src/proto/hardcopy.pro \
 		src/proto/hashtab.pro \
+		src/proto/indent.pro \
 		src/proto/json.pro \
 		src/proto/list.pro \
 		src/proto/main.pro \