Merge pull request #19 from abalabahaha/dev

fix(typings): DMChannel.createMessage optional file (abalabahaha#1488)

index.d.ts

@@ -3176,7 +3176,7 @@ declare namespace Eris {
     type: Constants["ChannelTypes"]["DM"];
     constructor(data: BaseData, client: Client);
     addMessageReaction(messageID: string, reaction: string, userID?: string): Promise<void>;
-    createMessage(content: MessageContent, file: FileContent | FileContent[]): Promise<Message<this>>;
+    createMessage(content: MessageContent, file?: FileContent | FileContent[]): Promise<Message<this>>;
     delete(): Promise<DMChannel>;
     deleteMessage(messageID: string): Promise<void>;
     editMessage(messageID: string, content: MessageContentEdit): Promise<Message<this>>;