New games, emoji tools and slash commands

Hello people!
There's multiple new things that came on Martine recently, so here is a little changelog:

• You can now get stats/infos from 3 new games, League of Legends, Minecraft, and Fortnite!
  • For LoL: Use lolstats which includes 3 subcommands all about stats of any summoner, and lolrotation for current free champions rotation.
    • For Minecraft: Use minecraft command group to see all subcommands.
    • For Fortnite: Use fortnite command followed by a player name (it must be an Epic username).
• Added emojis management commands. emojiadd emojiremove emojirename.
• Added support of Discord's Slash commands. All users interactions commands are now available as slash commands. Use slash command to see all currently available commands. If you don't see any Martine commands when typing /, that means that you have to re-authorize the bot, use invite command to do so, you don't need to kick the bot.
• YouTube music (music.youtube.com links) is now supported for music player.
• Added randomnsfw command, which is simply sending an nsfw image of a random category.
• Rework of help menu and help message of commands. Now by default when using help categoryname command, you will only see a list of each commands, if you want to see commands description simply append "details" at the end of the command, like help categoryname details.

Also splitted all settings related commands to help settings