Release v0.0.3

• added set-placeholder filter for dynamically setting (temporary) placeholders at runtime
• added --resume_from option to relevant readers that allows resuming the data processing from the first file that matches this glob expression (e.g., */012345.wav)
• requiring seppl>=0.2.17 now for resume, split group, skippable plugin support and avoiding deprecated use of pkg_resources
• to-adams-sp writer now uses -t short flag for the transcript like the from-adams-sp reader
• added the from-multi meta-reader that combines multiple base readers and returns their output
• added the to-multi meta-writer that forwards the data to multiple base writers
• using wai_common instead of wai.common now
• added split_group parameter to splittable writers (stream/batch)
• fixed the construction of the error messages in the pyfunc reader/filter/writer classes
• added metadata-to-placeholder filter to transfer meta-data files into placeholders