* PresentationOptions has gained more fine-tuning options:
* directivesEnd: specifies when `---` is written. ref #135
* containers: specifies whether containers use block or flow style
* suppressAddrs: if set, suppresses output of attributes
* quoting: specifies how strings should be quoted
* condenseFlow: specifies whether flow sequences should be on a
single line
* explicitKeys: specifies whether mapping keys should always have '?'
* PresentationStyle is now a list of presets that set
multiple options in PresentationOptions.
* Does not output trailing spaces anymore. ref #135
* Writes compact notation, i.e. a mapping in a sequence starts on the
line with the sequence's `-`, unless attributes are written
* Added tests for the presenter
* Existing code might change behavior because of whitespace, `---` and
compact notation. The API has been extended so that existing code is
affected as little as possible.
Felix Krause