Loading And Saving Refactoring

The current saveChanges() function is a bit of a monstrosity that casually combines a URI-parsing with saving backups, RSS feeds and full TiddlyWiki files. It is proposed to refactor this code so that it's possible to:

• add new save formats
• generalise the saving process to a sequence of:
  • obtain template via FileSystem?, AsyncXmlHttpRequest?, config.* string or contents of a tiddler
  • substitute file content (optionally filtered by an expression, title and other *-MARKUP-* elements
  • save to disc
  • (Note that upgrading the core code is implemented as a save operation where the template is obtained from http://www.tiddlywiki.com/empty.html)
• include an optional HTML StaticRendering of some or all tiddlers to support older/primitive browsers
• move the URI-parsing code into the FileSystem? module