Address to character

o useful in BibTeX entry coercions of the EML bibliography types

Related to issue #27
Adds more coercions to literature module

o now coercion
	thesis <-> bibentry possible
o also adds the coercion
	conferenceProceedings <-> bibentry

Related to issue #27
Adds personal communication citation coercion

o Adds coercions to `bibentry` for the rest of citation types
  as well but in comments only.

Belongs to issue #27
Merge pull request #80 from cpfaff/litrature

Litrature