[geary/wip/conversation-polish] Tidy up ConversationListStore's preview flags

[Michael Gratton <mjog src gnome org>]

commit 3cb5b92b9466979bcdbd40455a405466bb38d645
Author: Michael Gratton <mike vee net>
Date:   Fri Feb 1 11:43:09 2019 +1100

    Tidy up ConversationListStore's preview flags
    
    Per Bug 714317, we really just need to the message body, so just require
    that as a workaround for now.

 .../conversation-list/conversation-list-store.vala     | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)
---
diff --git a/src/client/conversation-list/conversation-list-store.vala 
b/src/client/conversation-list/conversation-list-store.vala
index be3e3998..1ef3fa09 100644
--- a/src/client/conversation-list/conversation-list-store.vala
+++ b/src/client/conversation-list/conversation-list-store.vala
@@ -14,13 +14,19 @@
  */
 
 public class ConversationListStore : Gtk.ListStore {
-    public const Geary.Email.Field REQUIRED_FIELDS =
-        Geary.Email.Field.ENVELOPE | Geary.Email.Field.FLAGS | Geary.Email.Field.PROPERTIES;
 
-        // XXX Remove ALL and NONE when PREVIEW has been fixed. See Bug 714317.
-        public const Geary.Email.Field WITH_PREVIEW_FIELDS =
-        Geary.Email.Field.ENVELOPE | Geary.Email.Field.FLAGS | Geary.Email.Field.PROPERTIES | 
Geary.Email.Field.PREVIEW |
-            Geary.Email.Field.ALL | Geary.Email.Field.NONE;
+    public const Geary.Email.Field REQUIRED_FIELDS = (
+        Geary.Email.Field.ENVELOPE |
+        Geary.Email.Field.FLAGS |
+        Geary.Email.Field.PROPERTIES
+    );
+
+    // XXX Remove REQUIRED_FOR_BODY when PREVIEW has been fixed. See Bug 714317.
+    public const Geary.Email.Field WITH_PREVIEW_FIELDS = (
+        REQUIRED_FIELDS |
+        Geary.Email.Field.PREVIEW |
+        Geary.Email.REQUIRED_FOR_MESSAGE
+    );
 
     public enum Column {
         CONVERSATION_DATA,