Add Unicode Block Elements

[hesselmonk]

Please add the Block Element characters to support more elaborate ASCII drawings like QR codes and other TUI applications:

Example:

                             
                             
    █▀▀▀▀▀█  █▄█▀ █▀▀▀▀▀█    
    █ ███ █ ▀█ █▀ █ ███ █    
    █ ▀▀▀ █   ▀ █ █ ▀▀▀ █    
    ▀▀▀▀▀▀▀ █▄▀▄█ ▀▀▀▀▀▀▀    
    ███ █▀▀███▀▀ ▀█▄ ▄█ ▄    
    ▀█▄▄ ▀▀█ ▀▀ ▀ ▄ █ ▀█▀    
    ▀ ▀▀ ▀▀ ▄▄▀▄▀▄▀█▄█▀ █    
    █▀▀▀▀▀█ █▄ █▄█▀█▀ ▀ █    
    █ ███ █ ▀██▀ ▀█▀██ █▀    
    █ ▀▀▀ █ ███ ▀ ▄▀█  ▄▀    
    ▀▀▀▀▀▀▀ ▀▀  ▀ ▀▀   ▀▀    
                             
                             

Related issues: #121 & #6

[morishxt]

@hesselmonk OK, I'll add them 👍