removed gender pronoun and updated message

The message wasn't very clear and there was a gender pronoun that slipped into it.
fixed : two users banning each other at the same time can crash the server
extended documentation of md.registerRenderer
tables in messages are now horizontally scrollable and don't break the layout
no more [delete] button on messages already deleted by an admin
Merge pull request #32 from rlemon/patch-1

removed gender pronoun and updated message
Merge branch 'youtube' of https://github.com/Ralt/miaou into Ralt-youtube
major style change
fixed a few problems with the youtube renderer

It was working on m.content, thus cancelling the work of previous renderers (including the markdown renderer). This also made it unable to find the <br>, which is why it couldn't work on multiline message. As it was returning true, it was also preventing other post-renderings.
Merge branch 'Ralt-youtube'
Merge branch 'master' of github.com:Canop/miaou
Uses the container width for calculations