mimefactory: remove unused "increation" field

src/mimefactory.rs

@@ -37,7 +37,6 @@ pub struct MimeFactory<'a, 'b> {
     timestamp: i64,
     loaded: Loaded,
     msg: &'b Message,
-    increation: bool,
     in_reply_to: String,
     references: String,
     req_mdn: bool,
@@ -152,7 +151,6 @@ impl<'a, 'b> MimeFactory<'a, 'b> {
             timestamp: msg.timestamp_sort,
             loaded: Loaded::Message { chat },
             msg,
-            increation: msg.is_increation(),
             in_reply_to,
             references,
             req_mdn,
@@ -194,7 +192,6 @@ impl<'a, 'b> MimeFactory<'a, 'b> {
             timestamp: dc_create_smeared_timestamp(context),
             loaded: Loaded::MDN,
             msg,
-            increation: false,
             in_reply_to: String::default(),
             references: String::default(),
             req_mdn: false,