Added 21 new icons:

• arrow-bl-circled
• arrow-bl-square
• arrow-br-circled
• arrow-br-square
• arrow-tl-circled
• arrow-tl-square
• arrow-tr-circled
• arrow-tr-square
• divide-three
• divide
• drag
• horizontal-merge
• horizontal-split
• page-down
• page-left
• page-right
• page-up
• path-arrow
• shortcut
• vertical-merge
• vertical-split