Settings

For the next bunch of commits I'm concentrating on the settings. I haven't intended these commits for 0.4.4, but feel free to pull whenever you like.  I'm going to push more commits either way. :)

Done:
- Make excerpt optional (#101)
- Do some ordering in the C++ files (settings)
- Let the user define the `maximumLineCount` for title and content (aka subtitle) in item list (#102)

Planed:
- …