Issue #2347783 by kim.pepper, andypost, almaudoh, gumanist, aleevas,...

Issue #2347783 by kim.pepper, andypost, almaudoh, gumanist, aleevas, rodrigoaguilera, Berdir, saurabh-2k17, Spokje, dhirendra.mishra, alexpott, paulocs, izus, Wim Leers, KapilV, naveenvalecha, anmolgoyal74, subson, yo30, harsha012, mrinalini9, daffie, voleger, dww, fietserwin, tim.plunkett, joachim, larowlan: Deprecate drupal_get_path() and drupal_get_filename() and replace with ExtensionList::getPath() and ExtensionList::getPathname()