Gradle migration

  - to run application interactively: `gradle run`
  - to run application tests: `gradle tvgs`
  - to see dependencies: `gradle dependencies`
  - to clean and rebuild: `gradle clean build check`
  - to see debug info append **-d** after any gradle command

TS definitions moved to folder `src/main/typesystem/`, every definition must be compliant with pattern `*_TS.xml`