Fix font in case Font.data is str

[penguinolog]

Font glyphs can fit in 1 string for some fonts

• Apply auto-format for examples/bigtext
• Use AttrMap instead of AttrWrap for BigText example

Checklist

• I've ensured that similar functionality has not already been implemented
• I've ensured that similar functionality has not earlier been proposed and declined
• I've branched off the master or python-dual-support branch
• I've merged fresh upstream into my branch recently
• I've ran tox successfully in local environment
• I've included docstrings and/or documentation and/or examples for my code (if this is a new feature)

[coveralls]

coverage: 73.565% (-0.005%) from 73.57% when pulling 4f621d6 on penguinolog:fix_font into 1ee80ce on urwid:master.