Implement custom platform directory when cloning a contest

[leonardo-delfino]

When cloning a contest, only one unique folder with a rather long name is created. Since the organization is not very practical, I implemented the creation of a folder with the name of the platform (Codeforces, AtCoder, etc.) and, inside of it, a second folder with the name of the cloned contest that contains the actual files.

[searleser97]

We need to make this change optional, please add a flag to the config file, the rest looks good

[leonardo-delfino]

Now you can set a flag in the config file to create the custom directory, otherwise the behavior is the same as before

[searleser97]

Thanks for this awesome contribution, merging...