- Closes simos#23
- This commit only fixes the Exception occurring when reading a file
  that contains a 'replace' directive. However it does nothing to
  actually process it!
  Therefore another commit is necessary to actually handle 'replace' (in
  addition to 'override').

- Closes simos#25
- Respects font style of selected font
- Better placement of texts by taking pango font metrics into account
- Use a bold font as default

- Larget default window size to have all texts fit by default