PEP8 fixes, several test files
Use RST table in MedLine docstring (was rendered as a paragraph)
PubMed file with multi-line MESH terms (MH lines).

Downloaded using this Entrez call,
Entrez.efetch(db=pubmed, id=23039619, rettype=medline, retmode=text)

See issue #286.
Test for multi-line MESH terms in Medline (issue #286)
Fix for parsing multi-line MESH terms in MedLine (closes #286)
We don't have upper/lower case variants of ThreeLetterProtein

This was brought up in discussion on issue #238.