Rotation of entire figure
Add a flag to rotate the entire HexPlot.
Hints: the new flag has to be defined in hex_plotter.cxx (e.g. --rotate 45) and passed over to the gep_plot class. Then it has to turn the x/y coordinates of every pad around the center 0/0. Check root_utils.cxx for the rotate_polygon function, which has a rotation implemented. Note however, that simply changing the position won't be enough, the pads have to be rotated themselves as well. So a rotation has to be appended to each transformation string.