[F/R] More Markdown Support

[Gamer92000]

The current Markdown support in the new client seems to be a bit lacking.

In every text field, I’d like to see support for the following things (with example implementation):

• sub- / superscript
  1^2^ => 1²
  1~2~ => 1₂

• underlined
  ++1++ => a̲

• blockquote
  > qoute =>

  quote

For things like channel and server description, I’d like to also see these things:

• Headers
  # Header =>

  Header

• Tables

  |a|b|
  |--|--|
  |c|d|
  

  =>

  a	b
  c	d

• Lists (Ordered and Unordered)

  - Item
  * Item
  
  1. Item
  2. Item
  

  =>

  • Item
  • Item
  1. Item
  2. Item

• Checklists

  * [ ] Item
  * [x] Item
  

  =>