Displays blocks in a fluid and responsive grid

syntax {up masonry=breakpoint:nbCols,margeX,margeY} block-1 block-2 block-n {/up masonry}
the main argument is the list of number of columns and margins per breakpoint.
Example :
{up masonry=960:4,1200:5} 4 columns above 960px, 5 if 1200px
{up masonry=960:4*10, 1200:5*10*20} same plus 10px XY margins for 960 and 10px X and 20px Y margins for 1200