Better integration of Masks

[luizfelippesr]

At present, Masks objects can be supplied to Likelihood objects, which use them to ignore the masked pixels in the likelihood calculation. However, it would be interesting to use, when possible, the same masks in the Simulators. The end of tutorial_masks illustrates (using "low level"ish operations) how hammurabi X can make use of a mask.

Plans for the Mask integration:

• The Simulator base class should include an argument for a masks dictionary in its __init__
• The Pipeline base should pass the likelihood to the Simulator
• There must be a way of making the user know if the Simulator can only handle a single mask
  • as this is the case of hammurabi X, and may be common,
  • one (crude but simple) possibility is requiring that masks of all the keys to be equal (raising an error otherwise)
• Whenever a Masks dictionary is provided by the user, the Hammurabi simulator must be updated internally, following the exact same procedure showed in the end of tutorial_masks (using the same temp directory used for dumping the Fields)
• Finally, tutorial_masks must be updated accordingly