Dont use `except:`!

This also triggers on KeyBoardInterrupt and SystemExit and can thus
prevent Python shutdown. Use `except Exception:` instead.
Merge pull request #176 from almarklein/no-naked-except

Dont use `except:`!
Merge branch 'gl-gloo-merge2' of github.com:vispy/vispy into gl-gloo-merge2

* 'gl-gloo-merge2' of github.com:vispy/vispy:
  Dont use `except:`!
Flakification