Block a user
fix #27 (core): no write permissions fail
[BUG]: program can't handle bad write permissions
fix #27 (core): no write permissions fail
[BUG]: Wrong output file extension
fix #25 (core): wrong output filename extensions when they are autodetected
fix #25 (core): wrong output filename extensions when they are autodetected
fix #18 (core): malformed names of output files
[BUG]: output names are malformed sometimes
fix #18 (core): malformed names of output files