Change version to 0.5.
Add EmptyDataSource.
Fixes null pointer exception.
Allow registering custom DataSources.
Fixes wrong separator for script placeholder.
Null or unknown values for placeholder will be displayed as empty string.
Table and list with null data sources will be skipped.
Add default constructor and display method to PrintPreviewPane.
Add `JsonDataSource`.
Add simple runnable editor and previewer.
Merge pull request #8 from davidjust/V0.5

V0.5