Fix a high priority bug with the masking system which was introduced in the switch to reconstructors classes

[allevitan]

There was a typo in the reconstructors class which broke the masking system. I noticed it today while working on a separate project.

I believe this change fixes it, and in addition I:

• Checked the entire file for all uses of "self" in recconstructors/base.py and the subclasses to check if any similar bugs had slipped by the earlier round of review
• Added a few lines to test_fancy_ptycho which will cause that reconstruction to fail with an unacceptably large error if the masking system stops working. I prefer folding it into the same test, rather than making a separate test, to keep the number of slow tests down.

[yoshikisd]

Thanks for catching this Abe! This all looks good to me. I also tested the pytest on my machine.