Cots entry validations

[Robin-M]

• [ ] The following entry is accepted: test/anime/38481 test/character/20622

I think it would be a good idea to include myanimelist.net in the url validation as well, so that if someone accidentally only copies part of the url the entry is rejected.

• [ ] The following entry is accepted: https://myanimelist.net/anime/38481/Toaru_Kagaku_no_Railgun_T https://myanimelist.net/character/17017/Kuroko_Shirai https://myanimelist.net/character/13701/Mikoto_Misaka

The validator should accept no more and no less than exactly one anime url and one character url.

• [ ] The following entry is accepted and results in only a preview for the first url: https://myanimelist.net/anime/38481/Toaru_Kagaku_no_Railgun_Thttps://myanimelist.net/character/17017/Kuroko_Shirai

Urls should be separated by at least one space or a linefeed so that the url previews will appear.

• [ ] The following entry is accepted: I think this entry should win because blablabla... https://myanimelist.net/anime/38481/Toaru_Kagaku_no_Railgun_T https://myanimelist.net/character/17017/Kuroko_Shirai

By validating the whole message, extra comments about the entry should not be accepted anymore.

• [ ] Entries that are already present are accepted. I think someone will eventually overlook one entry and post the same.