`seafile-ignore.txt` isn't powerful enough

Currently, seafile-ignore.txt only supports * and ? wildcards. Furthermore, it works completely different from .gitignore.

The main problem is in uses of glib's glob pattern matching, which covers only basics. You should write your own function for pattern matching, which will work the same as .gitignore file because it's expected from the ignore file.

After my investigation, I found seaf_repo_check_ignore_file in daemon/repo-mgr.c, which looks like what I looked for. Unfortunately, I'm too bad in C, and I can't make requested here changes myself.

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I also found few other issues with same proposes (#875, #762 and maybe some others) which were silently closed, I hope this feature request will not be the next?