Add --version

[vmdocua]

Corresponds to these issues:

• Refactor C++ code #61
• Make it possible to reload configuration if config file changes #69
• Closes Upon interruption (Ctrl-C) make it to exit gracefully #70

@yarikoptic merged all those as of 61edd29 and now ongoing development on a solution for

• Closes Add --version #72

[yarikoptic]

is that a PR which makes ffmpeg run in a separate thread? If so -- could you add writing those stdout/stderr into some .log file along with .mkv so we could later troubleshoot e.g. issues like #73? Then file also should be renamed accordingly as well along with .mkv during that one getting renamed.

Generally please give PR title/summary semantic description of changes , issues should be pointed to in description.