Issue #1589968 by cr0ss, Cottser, Pancho, DarthDrupal, Mark Carver: Move Title from process to preprocess, remove template_process_page().

Issue #2013094 by pwieck, Cottser: Remove unnecessary template_preprocess() reference from all Twig files

Issue #1363112 by mparker17, mgifford, tlattimore, Jacine, dcmouyard, bowersox, ry5n, ahdiaz: Simplify names of 'element-x' helper classes.

Issue #1961870 by Cottser, foopang, kgoel, shanethehat, tlattimore, c4rl, joelpittet, thedavidmeister: Convert page.tpl.php to Twig.