Removes the changing of the leader key

The pause when pressing comma was annoying
Changes mac vim font to menlo

This enables bold and italic type facing for
markdown highlighting especially, and it matches
sublime text, and it does look ok
Adds ll mapping and allows less to print colours
Makes link from mkd to markdown ftplugin

As the markdown-vim plugin changes the type to mkd
this mapping allows control for both filetypes
simultaneously