Markdown improvements

Markdown improvment roadmap:

• automatic hyper link (<a> for url)
• fix sublist
• generate html for given html code
• blank click for external link
• handle tab in tension comment
• add a notice that show markdown helps
• ability to striketrough a task.
• emoji
• user link: @*** -> [@***](https://fractale.co/user/***)
• tension link: #0x*** -> [#0x***](/tension//0x*****)
• circle link: o/xxx -> [o/xxx](/o/xxx)
• search tension/circle by typing (like emoji !)
• ability to click check box (new tension event with no mail notif? not yet)
• ability to move task around (change order).
• count first comment checkboxes and sync it in a new tension propertie to show the prop of avancement of the tension.
• attach image !
• create table (select number row/column) in input
• switch to rich text edition !?

ressources:

• https://github.com/dillonkearns/elm-markdown

• https://ellie-app.com/8kHgbSLfhfha1