added resplit to None for slicing with DNDarrays

[coquelin77]

Description

Update to slicing with DNDarrays

Issue/s resolved: n/a

Changes proposed:

• resplit to split None if the key given to the DNDarray getitem is itself a DNDarray

Type of change

• Bug fix (non-breaking change which fixes an issue)

Due Diligence

• All split configurations tested
• Multiple dtypes tested in relevant functions
• Documentation updated (if needed)
• Updated changelog.md under the title "Pending Additions"

Does this change modify the behaviour of other functions? If so, which?

yes, possibly. If a function was working with unbalanced DNDarrays then this slicing scheme would cause issues

[codecov]

Codecov Report

Merging #635 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #635   +/-   ##
=======================================
  Coverage   97.52%   97.52%           
=======================================
  Files          77       77           
  Lines       16102    16105    +3     
=======================================
+ Hits        15704    15707    +3     
  Misses        398      398           

Impacted Files	Coverage Δ
heat/core/dndarray.py	97.22% <100.00%> (+0.01%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6d7c95c...87b7da7. Read the comment docs.