remove intention to implement \important special-use mailbox and $important message flag, rfc 8457

they are intended to be used by the server to automatically mark some messages
as important, based on server-defined heuristics. we don't have such heuristics
at the moment. perhaps in the future, but until then there are no plans.

webmail/api.json

@@ -1631,7 +1631,7 @@
 				},
 				{
 					"Name": "Draft",
-					"Docs": "",
+					"Docs": "\"Drafts\"",
 					"Typewords": [
 						"bool"
 					]
@@ -3120,7 +3120,7 @@
 				},
 				{
 					"Name": "Draft",
-					"Docs": "",
+					"Docs": "\"Drafts\"",
 					"Typewords": [
 						"bool"
 					]

webmail/api.ts

@@ -192,7 +192,7 @@ export interface Mailbox {
 	UIDValidity: number  // If UIDs are invalidated, e.g. when renaming a mailbox to a previously existing name, UIDValidity must be changed. Used by IMAP for synchronization.
 	UIDNext: UID  // UID likely to be assigned to next message. Used by IMAP to detect messages delivered to a mailbox.
 	Archive: boolean
-	Draft: boolean
+	Draft: boolean  // "Drafts"
 	Junk: boolean
 	Sent: boolean
 	Trash: boolean
@@ -498,7 +498,7 @@ export interface ChangeMailboxSpecialUse {
 // understand where messages should go.
 export interface SpecialUse {
 	Archive: boolean
-	Draft: boolean
+	Draft: boolean  // "Drafts"
 	Junk: boolean
 	Sent: boolean
 	Trash: boolean