Memoizer errs (rebased onto develop)



This is the same as gh-1143 but rebased onto develop.

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`.bfmemo` file creation is failing for `ZeissCZI` files leading to slow loading times. This PR should help determine the problem by showing the complete stacktrace. Once found, this PR can be closed. Alternatively, a "verbose" argument can be added to the constructor for configuring logging levels.