Metro mode
[gallery mode="metro" columns="1 / 2 / 3 / 4 / 5 / 6" first_big="true / false" ids="0001,0002,0003…n"]
Slideshow mode
[gallery mode="slideshow" width="3" height="2" ids="0001,0002,0003,0004…n"]
Default mode
[gallery ids="0001,0002,0003,0004…n"]