refactor and cleanup [skip ci]

submodules/Postbox/Sources/Upgrades.swift

@@ -0,0 +1,25 @@
+import Foundation
+import SwiftSignalKit
+
+enum PostboxUpgradeOperation {
+    case inplace((MetadataTable, ValueBox, (Float) -> Void) -> Void)
+    case standalone((Queue, String, ValueBox, ValueBoxEncryptionParameters, (Float) -> Void) -> String?)
+}
+
+func registeredUpgrades() -> [Int32: PostboxUpgradeOperation] {
+    var dict: [Int32: PostboxUpgradeOperation] = [:]
+    dict[12] = .inplace(postboxUpgrade_12to13)
+    dict[13] = .inplace(postboxUpgrade_13to14)
+    dict[14] = .inplace(postboxUpgrade_14to15)
+    dict[15] = .inplace(postboxUpgrade_15to16)
+    dict[16] = .inplace(postboxUpgrade_16to17)
+    dict[17] = .inplace(postboxUpgrade_17to18)
+    dict[18] = .inplace(postboxUpgrade_18to19)
+    dict[19] = .inplace(postboxUpgrade_19to20)
+    dict[20] = .inplace(postboxUpgrade_20to21)
+    dict[21] = .standalone(postboxUpgrade_21to22)
+    dict[22] = .inplace(postboxUpgrade_22to23)
+    dict[23] = .inplace(postboxUpgrade_23to24)
+    dict[24] = .inplace(postboxUpgrade_24to25)
+    return dict
+}