Make use of Greek and Latin letters consistent, https://github.com/Frege/frege/issues/76
do not greekify implementation vars
small documentation update (from list-like to list-view)
some comments for review
finishing issue #76 for the PreludeList
greek letters for top-level function declarations
Merge pull request #79 from Frege/greek_letters_issue_76

Greek letters issue for PreludeList, thank you Dierk