Richer lifecycle events API.

..
    This file is part of lazr.lifecycle.

    lazr.lifecycle is free software: you can redistribute it and/or modify it
    under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, version 3 of the License.

    lazr.lifecycle is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
    License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with lazr.lifecycle.  If not, see <http://www.gnu.org/licenses/>.
