tour.py: update Padding widgets to use left, right parameters; add max_width for GridFlow Padding
tour.py: update Padding widgets to use left, right parameters; add max_width for GridFlow Padding

--HG--
branch : feature-containers

foreni-packages/urwid,westurner/urwid,bk2204/urwid,zyga/urwid,hkoof/urwid,inducer/urwid,harlowja/urwid,douglas-larocca/urwid,inducer/urwid,mountainstorm/urwid,drestebon/urwid,tonycpsu/urwid,Julian/urwid,wardi/urwid,foreni-packages/urwid,rndusr/urwid,harlowja/urwid,inducer/urwid,wardi/urwid,harlowja/urwid,westurner/urwid,zyga/urwid,mountainstorm/urwid,ivanov/urwid,hkoof/urwid,tonycpsu/urwid,bk2204/urwid,mountainstorm/urwid,drestebon/urwid,Julian/urwid,rndusr/urwid,urwid/urwid,hkoof/urwid,ivanov/urwid,tonycpsu/urwid,bk2204/urwid,douglas-larocca/urwid,rndusr/urwid,drestebon/urwid,Julian/urwid,zyga/urwid,westurner/urwid,foreni-packages/urwid,ivanov/urwid,douglas-larocca/urwid,urwid/urwid,wardi/urwid,urwid/urwid