Py3: make generators tests compatible with Python 3.3
Py3: make a few files in Generator compatible with Python 3.3
Py3: fix imports in 'Toolbox/optimizers' tests
Py3: make '__init__.py' compatible with Python 3.3
Py3: make {Events,Variable}.py compatible with Python 3.3
Py3: make 'utils.py' compatible with Python 3.3
Py3: make 'common.py' compatible with Python 3.3
Py3: make 'parseUtils.py' compatible with Python 3.3
Py3: make 'Points.py' compatible with Python 3.3
Py3: make 'Interval.py' compatible with Python 3.3
Py3: make 'FuncSpec.py' compatible with Python 3.3
Py3: make 'Symbolic.py' compatible with Python 3.3
Py3: make code generators compatible with Python 3.3
Py3: make 'Trajectory.py' compatible with Python 3.3
Py3: make 'Generator/ODESystem.py' compatible with Python 3.3
Py3: make 'Generator/Euler_ODEsystem.py' compatible with Python 3.3
Py3: make 'Generator/Vode_ODEsystem.py' compatible with Python 3.3
Py3: make 'scipy_ode.py' compatible with Python 3.3
Py3: make 'Generator/Dopri_ODEsystem.py' compatible with Python 3.3
Py3: make 'integrator.py' compatible with Python 3.3