Added fix to make sure that subtitle_marks are always before adjacent gap_marks
Removed syncing of AT to PT in /content. Moved code to `rt export plain_kramdown` command.
Extended rtfile DSL: added settings
Refactored renaming of files for subtitle_tagging import and export
Updated subtitle_tagging converter: normalize file end + comments
Replaced hard-coded converter method invocation with one that is configurable via rtfile
Updated fix adjust_merged_record_mark_positions: make sure that first record_mark is followed by blank line
Repositext::Cli::Utils: when moving files, make output_path_lambda configurable so that we can also rename files when moving them to a different directory.
Update Repositext::Validation: Add method to validate file pairs
Updated kramdown syntax validators:

* reset StringScanner instead of creating new instance for improved performance
* added validation to make sure that all record_marks are followed by a blank line
* updated comments
Updated ICML export to use AT files instead of PT ones (they are now gone)
Added subtitle_tagging import command