Pubmed-parser

- Add test to the repository
- Update docstrings, function renaming
- Functional correction for MEDLINE test
- Overall code updates

- Minor fix for string literal

- update MEDLINE parser, now can parse issue, page number, and first name
- Fix error parsing PubMed XML
- Fix some syntax errors when parsing

Final version for JOSS submission

Pubmed Parser for JOSS publication
- Fix documentation
- Fix paper and references

- Full documentation of Pubmed Parser
- Code mostly fixed for recent dataset