added new tool to do overlap removal. Works only on UFO fonts. This uses Frederick Berlaen's booleanOperations github library. This is still work in progress. The behavior is not the same as the FDK checkOutlines tool. One difference is that in checkOutlinesUFO, contours are merged if a corner point on one outline lies on the path of the other outline; this does not happen in checkOutlines. There are also some bugs to resolve. When two curves intersect, if they are long and nearly flat at the intersection point, checkOutlinesUFO will insert a short straight line at the end of the incoming curve. Another is that if there is a small jog in a path ( two consecutive near right angles, with a short path between), it will get sanded off in checkOutlinesUFO.  The output is written to an alternate layer in the UFO font: to see the output, you need to use 'tx' to copy it to a new font, ufo or Type1.