Build a WYSIWYG editor

[maheshj01]

Ditch the preview section and build a editor to show markdown Via a tooltip menu

• Add a new editor with markdown support from scratch
• Expose keyboard shortcuts for this editor
• This menubar is shown when a particular piece of text is selected
• This menubar will contain markdown commands
• Selecting a command on menubar will apply the style to that particular piece of text
• Styles should also be applied using keyboard shortcuts