OO-725 implement separation of transcoding dir and master video in repo, implement missing transcoding preview, moved poster generation to tmp

OO-725 rename type to resolution, use getter/setter conventions, missing i18n keys, fix modul initialization

OO-725 implement missing import/export, synchronize posterframe and repo entry image (one way), cleanup api, move things to manager

OO-1994: changed validation to validate folder names aswell. added own error message for folder name errors