Rotates the transformation matrix in JOSM .png.cal calibration files by a given number of degrees, without needing to re-calibrate from scratch.
Place the script in the same directory as your .png.cal files and run it. An interactive menu lets you choose between three modes: Single to rotate one file by exact name, Multiple to rotate a set of files matching a shared prefix, suffix, or both, and All to rotate every .png.cal file in the directory. For each operation you'll be prompted for the direction (clockwise/counter-clockwise) and degrees of rotation.