added NOTHING to STypes.BASIC_TYPES and EMPTY_ARRAY to STypes.ARRAY_TYPES
redesigned DefinedFunctionsCreator to handle array literals with elements of different types and create array with element type equal to common super type of element types
moved ArtifactSaverSmoothTest to .base package
added tests checking that creation of array containing String value and value of other type causes error
renamed smooth function contentOf -> toBlob
updated changelog.md
refactored ValueDbTest
removed elements sorting from arrays stored in ValueDb
added concatenateFiles smooth function
removed merge smooth function