template.summary(scope,min_chars) is now template.first_sentences(scope,min_chars). Added template.render_plaintext(scope)

Fixed summary implementation.
Implemented page.atom_id fallbacks generation. Fixed page.summary bug (manual summaries were being converted to nil)
Implemented app.url_for in core, removed from Nesta. Fixed 'page is nil' bug.
Modified wordpress URL regexes to handle newlines properly if encountered for some reason.