#46 Batch convert by manually setting rectangles

Hello,

It would be nice to be manually able to set the rectangles while batch converting. For instance:

java -jar briss-0.9.jar -s in.pdf -d out.pdf --coordinates "x0=150 x1=200 y0=40 y1=60, x0=120 x1=160 y0=20 y1=130"

to batch crop the pdf with two rectangles on each page.