Optimize json processing and preloading

- Preload events when added to the EventHolder queue
- Remove relative time formatting from preloader. Just do it when event appears
- Process incoming json in a background queue by default

Changelog-Fixed: Fix wrong relative times on events
Changelog-Changed: Preload events when they are queued

damus/Models/ProfileModel.swift

@@ -8,20 +8,27 @@
 import Foundation
 
 class ProfileModel: ObservableObject, Equatable {
-    var events: EventHolder = EventHolder()
     @Published var contacts: NostrEvent? = nil
     @Published var following: Int = 0
     @Published var relays: [String: RelayInfo]? = nil
     @Published var progress: Int = 0
     
+    var events: EventHolder
     let pubkey: String
     let damus: DamusState
     
-    
     var seen_event: Set<String> = Set()
     var sub_id = UUID().description
     var prof_subid = UUID().description
     
+    init(pubkey: String, damus: DamusState) {
+        self.pubkey = pubkey
+        self.damus = damus
+        self.events = EventHolder(on_queue: { ev in
+            preload_events(state: damus, events: [ev])
+        })
+    }
+    
     func follows(pubkey: String) -> Bool {
         guard let contacts = self.contacts else {
             return false
@@ -47,11 +54,6 @@ class ProfileModel: ObservableObject, Equatable {
         return .pubkey(pubkey)
     }
     
-    init(pubkey: String, damus: DamusState) {
-        self.pubkey = pubkey
-        self.damus = damus
-    }
-    
     static func == (lhs: ProfileModel, rhs: ProfileModel) -> Bool {
         return lhs.pubkey == rhs.pubkey
     }