Translate the bot on its entirety into English

[jkcgs]

Including modules, logs, documentation, etc. Of course, modules will still be available in Spanish.

• [x] Modules
• [x] Logging
• [x] Comments
• Documentation

The documentation will be left for some time soon:tm:

Changelog

Translations

• All the texts in the code have been translated into English (comments, docstrings and logging)
• All output texts (the ones sent to Discord) are now translatable
• Logged texts are parsed by the language filter first
• Language can now have a specific channel
• The language to use with a user via PM is now determined by common servers or the message event instead of using the default language
• Fixed language strings being parsed twice, but they can now be recursive (adding a language placeholder inside a language string)
• Language strings can now have lists, accessible with the Language.get_list method
• Changed the placeholder for inexistant language strings to [lang:string_name]
• All texts for language are now processed on the lang_filter module.
• The Language class will use the default language for servers without it's own language set, without storing it in the database.

Commands

• !lang now displays the current server and channel languages, and displays the info inside a modal. It accepts a new format: !lang [channel | here] <lang | unset>.
• !status can now receive a pipe-separated list of status which can replace the normal lambdas of status texts. They can be unset by simply using !status without parameters.
• Booru-like image search commands have been merged into a single module, and they are now even more: e621, gelbooru, rule34, danbooru, konachan, konachan18, hypnohub, xbooru, realbooru, furrybooru. The command is !booru [type] [search_string], and it's available only in NSFW channels (the ones that its name contains "nsfw").

Others

• Command author is not displayed on CommandEvent.answer by default
• Even the lang.py script (command line script to manage language strings) has been translated into English
• utils.img_embed now accepts a footer parameter
• It will filter out the prefix if a message to be sent starts with the command prefix.
• Only one person is now displayed as the bot's author
• General system stability improvements to enhance the user's experience.

[jkcgs]

I feel that this PR is now ready, it will be in testing for a couple or days or less, available at the #bots r/chile's guild, with the , prefix.