Add note on how to handle fatal errors, as per mailing list
merged branch igorw/cookbook-fatal (PR #735)

This PR was merged into the 1.0 branch.

Discussion
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Add note on how to handle fatal errors

I'm not so happy with this solution from a usability perspective, but I don't want to have global error handlers in silex itself.

An option we could consider is making symfony's ErrorHandler fall back to an internal ``ExceptionHandler`` for fatal errors. But obviously that is not very elegant either. Ideas welcome.

Commits
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7a222ce Add note on how to handle fatal errors, as per mailing list