Supported custom script variables for folder names

• Source.Name
• Extraction.ExtractionName
• Extraction.Type
• Extraction.SapObjectName
• Extraction.Context (only contains values for ODP extractions)
• Extraction.Timestamp

Additional changes

• File splitting uses the JEDEC definition of MB now, i. e. it counts powers of two instead of ten (all destinations)
• Folder name for Azure Storage is written to extraciton log