Code formatting

Closes #332
Don't die on all exceptions

This is annoying, since most things are just stuff we haven't anticipated. Yes,
you can probably get into some unrecoverable states, but it's highly likely
you'll be able to save your work and exit gracefully, instead of just having
the WM crash hard.

Also, catch a BadDrawables, since they're products of the same race as
BadAccess and BadWindow.

Closes #340