[geary/wip/778276-better-flag-updates: 2/25] Fix some engine build warnings.

[Michael Gratton <mjog src gnome org>]

commit d40ad83b6c934d3bd9387f8eed9cf90e68435021
Author: Michael James Gratton <mike vee net>
Date:   Sat Dec 2 00:55:33 2017 +1100

    Fix some engine build warnings.
    
    * src/engine/imap/command/imap-create-command.vala: Enums can't be null?
    
    * src/engine/rfc822/rfc822-message.vala: Gee.Map has deprecated contains?!

 src/engine/imap/command/imap-create-command.vala |    9 +++++++--
 src/engine/rfc822/rfc822-message.vala            |    2 +-
 2 files changed, 8 insertions(+), 3 deletions(-)
---
diff --git a/src/engine/imap/command/imap-create-command.vala 
b/src/engine/imap/command/imap-create-command.vala
index 5da3d1e..f09d8bc 100644
--- a/src/engine/imap/command/imap-create-command.vala
+++ b/src/engine/imap/command/imap-create-command.vala
@@ -15,7 +15,10 @@ public class Geary.Imap.CreateCommand : Command {
     public const string USE = "use";
 
     public MailboxSpecifier mailbox { get; private set; }
-    public Geary.SpecialFolderType? use { get; private set; default = null; }
+
+    public Geary.SpecialFolderType use {
+        get; private set; default = Geary.SpecialFolderType.NONE;
+    }
 
 
     private static MailboxAttribute? get_special_folder_type(Geary.SpecialFolderType type) {
@@ -52,8 +55,10 @@ public class Geary.Imap.CreateCommand : Command {
         add(mailbox.to_parameter());
     }
 
-    public CreateCommand.special_use(MailboxSpecifier mailbox, Geary.SpecialFolderType use) {
+    public CreateCommand.special_use(MailboxSpecifier mailbox,
+                                     Geary.SpecialFolderType use) {
         this(mailbox);
+        this.use = use;
 
         MailboxAttribute? attr = get_special_folder_type(use);
         if (attr != null) {
diff --git a/src/engine/rfc822/rfc822-message.vala b/src/engine/rfc822/rfc822-message.vala
index a2e2868..267203a 100644
--- a/src/engine/rfc822/rfc822-message.vala
+++ b/src/engine/rfc822/rfc822-message.vala
@@ -211,7 +211,7 @@ public class Geary.RFC822.Message : BaseObject {
                     string cid = "";
                     do {
                         cid = CID_TEMPLATE.printf(cid_index++);
-                    } while (cid in email.cid_files);
+                    } while (email.cid_files.has_key(cid));
 
                     if (email.replace_inline_img_src(name,
                                                      CID_URL_PREFIX + cid)) {