Refactor code to get rid of AbstractTopLevelDefinition

According to sgandon we have a new class I18nDefinition which was designed for the same purposes as AbstractTopLevelDefinition, but was moved to Daikon project. We need to get rid of old AbstractTopLevelDefinition class in TCOMP and replace its usage with I18nDefinition.

Ivan:
Found following issues to solve:

1. PropertiesImpl implements both: AnyProperty, Properties interfaces. However Properties extends AnyProperty, so Properties is enough
2. Following classes duplicates getDisplayName() method (i18n version): PropertyPathConnector, AbstractTopLevelDefinition, I18nDefinition, PropertiesImpl, Property, Form
3. Should PropertyPathConnector be internationalized at all?
4. Do we need SimpleNamedThing (not internationalized named thing)?
5. PresentationItem has no i18n (but I think button should have i18n)
6. DatasetProperties has no abstract class (Seems they may have a class with getDatastoreProperties() methods)
7. IOProperties has no parent abstract class

Steps:

1. Check all inheritors of SimpleNamedThing