Add experimental support for unified_card

Closes #345

src/experimental/types/unifiedcard.nim

@@ -0,0 +1,79 @@
+import options, tables
+from ../../types import VideoType, VideoVariant
+
+type
+  UnifiedCard* = object
+    componentObjects*: Table[string, Component]
+    destinationObjects*: Table[string, Destination]
+    mediaEntities*: Table[string, MediaEntity]
+    appStoreData*: Table[string, seq[AppStoreData]]
+
+  ComponentType* = enum
+    details
+    media
+    swipeableMedia
+    buttonGroup
+    appStoreDetails
+    twitterListDetails
+    communityDetails
+    mediaWithDetailsHorizontal
+
+  Component* = object
+    kind*: ComponentType
+    data*: ComponentData
+
+  ComponentData* = object
+    id*: string
+    appId*: string
+    mediaId*: string
+    destination*: string
+    title*: Text
+    subtitle*: Text
+    name*: Text
+    memberCount*: int
+    mediaList*: seq[MediaItem]
+    topicDetail*: tuple[title: Text]
+
+  MediaItem* = object
+    id*: string
+    destination*: string
+
+  Destination* = object
+    kind*: string
+    data*: tuple[urlData: UrlData]
+
+  UrlData* = object
+    url*: string
+    vanity*: string
+
+  MediaType* = enum
+    photo, video
+
+  MediaEntity* = object
+    kind*: MediaType
+    mediaUrlHttps*: string
+    videoInfo*: Option[VideoInfo]
+
+  VideoInfo* = object
+    durationMillis*: int
+    variants*: seq[VideoVariant]
+
+  AppType* = enum
+    androidApp, iPhoneApp, iPadApp
+
+  AppStoreData* = object
+    kind*: AppType
+    id*: string
+    title*: Text
+    category*: Text
+
+  Text = object
+    content: string
+
+  HasTypeField = Component | Destination | MediaEntity | AppStoreData
+
+converter fromText*(text: Text): string = text.content
+
+proc renameHook*(v: var HasTypeField; fieldName: var string) =
+  if fieldName == "type":
+    fieldName = "kind"