Saving session data (spydata) deletes all arrays nested inside other data structures

[CAM-Gerlach]

Problem Description

In fixing #919 and writing more comprehensive tests for Spyder's save_dictionary and load_dictionary session spydata save/load functions, I discovered that saving one's session will delete all arrays that are not top-level, i.e. those inside lists, dictionaries, etc from the user's active session, during the process of removing them to be serialized separately. The fix is a simple one (just deepcopying the data passed to the save_dictionary function and a PR should be up shortly, but I thought I'd open this issue to document the problem.

What steps will reproduce the problem?

1. Create a list or dictionary with a numpy array inside of it
2. Save the session
3. View the list/dictionary again

What is the expected output? What do you see instead?

Expected: Array is not removed. Actual: Array is.

Package Versions

• Spyder: 3.2.7
• Python: 3.6.4
• Qt: 5.6.2
• PyQt: 5.6
• Operating System: Win 8.1 Pro x64