fontView: Set column titles and disable sorting

Also handle some KeyError exceptions
fontView: Use relative imports and shorter namespaces
Handle fontTools.ttLib.TTLibError errors
Show the length of tables in bytes, like `ttx -l'

But not formatting the numbers, as we don't have any locale set
Merge pull request #2 from behnam/master

fontView: Set column titles and disable sorting
Minor
Fix GlyphCoordinates

It's embarrassing that I failed to test ttx completely.

https://github.com/behdad/fonttools/issues/4
Merge http://github.com/behdad/fonttools