Huge refactoring to use new compiler and deprecate all other Packers

Add new PdfPacker

demo/demo1.js

@@ -1,4 +1,5 @@
 const docx = require('../build');
+const fs = require('fs');
 
 var doc = new docx.Document();
 
@@ -10,7 +11,10 @@ paragraph.addRun(dateText);
 
 doc.addParagraph(paragraph);
 
-var exporter = new docx.LocalPacker(doc);
-exporter.pack('My Document');
+var packer = new docx.Packer();
+
+packer.toBuffer(doc).then((buffer) => {
+    fs.writeFileSync('My Document.docx', buffer);
+});
 
 console.log('Document created successfully at project root!');