remove from API delete()/IsDeleted(), and deleted check from prepForXml; not useful in declarative style API

src/file/xml-components/base.ts

@@ -9,16 +9,10 @@ export interface IContext {
 
 export abstract class BaseXmlComponent {
     protected readonly rootKey: string;
-    // tslint:disable-next-line:readonly-keyword
-    protected deleted: boolean = false;
 
     constructor(rootKey: string) {
         this.rootKey = rootKey;
     }
 
     public abstract prepForXml(context: IContext): IXmlableObject | undefined;
-
-    public get IsDeleted(): boolean {
-        return this.deleted;
-    }
 }