Changes to the Noise class to store only local detectors.

[tskisner]

• Remove the internal noise model from the focalplane class. Focalplanes have information about all detectors (not only the locally stored ones).

• Add methods to the Noise base class and the AnalyticNoise derived class to handle gather / scatter / redistribution of noise model data.

• Update the hdf5 I/O methods to use these new functions for when reading / writing.

• When redistributing observations, any metadata objects that define a redistribute() method will have that called.

• Update ElevationNoise, NoiseEstim, and FitNoiseModel operators to match the API changes to the noise model.

• Fix warnings throughout the code due to the use of "np.int", "np.int_", and "np.float" types.

[tskisner]

Just a note on this PR. The CMBenv docker containers used to test extra dependencies on linux include an MPI enabled HDF5 / h5py which seems to have a problem. I have run the unit tests in this branch locally in a conda environment with 4 processes using hdf5-mpi installed from conda packages. Our cmb stack is in the process of being updated, but that should not hold up this PR. Will merge once MacOS tests pass.