Uncaught exceptions always print previous ones.
Add Hoa\Core\Exception\Group.

A Hoa\Core\Exception\Group instance is an exception that contains a
group of exceptions.
[auto] Merge from Core

    • #023e473 — Uncaught exceptions always print previous ones. (Ivan Enderlin, 2013-06-07)
    • #ed3bb09 — Add Hoa\Core\Exception\Group. (Ivan Enderlin, 2013-06-07)

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Merge remote branch 'library-core/master'