JDFTXOutfileSlice Durability Improvement

[benrich37]

Summary

Major changes:

• feature 1: Improved durability of JDFTXOutfileSlice._from_out_slice method (less likely to error out on unexpected termination)
  -- So long as one step of electronic minimization has started on an out file slice, parsing shouldn't error out
• fix 1: Allow partially dumped eigstats
• fix 2: Added missing optical band gap dumped by eigstats
• fix 3: Protect the final JOutStructure in initializing a JOutStructures with a try/except block
• fix 4: Detect if positions were only partially dumped and revert to data from init_structure in JOutStructure
• fix 5: Prevent partially dumped matrices from being used in initializing a JOutStructure

Todos

• feature 1: Ensure parse-ability as long as a JDFTXOutfileSlice.infile can be initialized