Preparing the application for use of Preferences:
- Introduced a new Window architecture
- Moving properties from TaskProperties to AppPreferences
- Prepared a new Serializable TaskSet object and a Serializer for
persistence into Preferences
Merge branch 'master' of git@github.com:cyChop/daily-tasks.git
Prepared for locally stored preferences

Prepared some UI elements for a settings window
Javadoc for previously created classes