Ability to delete custom actions from within the UI (thanks @albertospelta)
Major improvements to ExportProperties / ImportProperties (thanks @albertospelta). How would you like to edit object translations, perspective membership, etc. in an Excel sheet?
Preparations for the upcoming Power BI Desktop "External Tools" integration. For example, there's a new setting under File > Preferences, which will cause Tabular Editor to automatically detect changes made to a Power BI Desktop model from inside Desktop, refreshing the TOM tree in Tabular Editor. The setting is enabled by default, but since this feature is using Analysis Services Tracing, you can disable it if it's causing any kind of issues.
Database Compatibility Level can now be modified from inside the UI, making it possible to upgrade models from 1200->1400, 1400->1500 and 1500->1520. Please note that you cannot upgrade a model using the Deployment Wizard. Instead, open the model from an existing database, change the compatibility level, and hit save.
Table and Column objects now display a dropdown on their DataCategory property (see #498). The dropdown is populated with values according to the MS-SSAS-T specification.