Check error handlers for specific classes first

This allows adding error handlers like this:

    @app.errorhandler(werkzeug.exceptions.Forbidden)

And subclassing HTTPExceptions:

    class ForbiddenBecauseReason(Forbidden): pass

    @app.errorhandler(ForbiddenBecauseReason)
    def error1(): return "Forbidden because reason", 403
    @app.errorhandler(403)
    def error2(): return "Forbidden", 403

... the idea being, that a flask extension might want to raise an
exception, with the default behaviour of creating a HTTP error page,
but still allowing the user to add a view/handler specific to that
exception (e.g., "Forbidden because you are not in the right group").
Fix import in viewdecorators.rst for @templated
Tweak wording in viewdecorators.rst
missed word.

request tstack -> request context stack
Updated changelog formatting
Added workaround for Python 3.3's frozen loader
Fixed the last changeset.
Better support for namespace packages.
fix typo
Fix minor typo
Merge pull request #1022 from mjfroehlich/patch-1

Fix minor typo
Merge pull request #1019 from raimu/master

fix typo
Merge pull request #1012 from atupal/patch-2

missed word.
Fixed intention in flask init
Added the new flask run module to start the server.
Merge branch 'master' of github.com:mitsuhiko/flask
Added thread flag to flask run
Fixed a reference in the docs.
Added __main__ module
Fix typos in docstrings and comments in run.py