Log Message:
Update to 3.50. From the changelog:

- added lineno, column parameters to OnStateChange hook
- added support for Crystal (thanks to C R Jaensch)
- added support for Slim (https://gitlab.com/saalen/highlight/merge_requests/85)
- fixed several typos in documentaion and manpages
- CLI: added `--syntax-by-name` option (suggested by Chris Mayo)
- CLI: removed deprecated `--list-langs` and`--list-themes` options
- GUI: added terminal sequence output options \ 
(https://gitlab.com/saalen/highlight/issues/110)