Check if `loadStructure` and other file loading functions accept `pathlib.Path`

[Tieqiong]

Problem

Check if loadStructure and other file loading functions accept pathlib.Path.

Proposed solution

Fix if not

[kwagoner94]

I will take this issue.

[stevenhua0320]

Closes this issue as finished by PR #185

[sbillinge]

closing per @stevenhua0320