Allow upgrading applications with pages that have been moved/renamed

Currently EM doesn’t know how to follow renames when upgrading so for example if I move pages from the FAQCode space to the FAQ.Code space, when EM upgrades the app, it’ll display all pages in FAQCode as deleted (basically it considers all pages in FAQ.Code as new pages and pages in FAQCode as deleted pages).

Some ideas:

• An extension could provide some metadata (for example in the package.xml) to link pages. For example:

      <file language="" defaultAction="0" alias="FAQCode.WebHome">FAQ.Code.WebHome</file>
  

• Even better, EM could also automatically discover similar files by computing a hashcode of a page to find renames.