Merge pull request #76 from Skeen/master

out-of-source building + more
Fix building libclipper.a all the time after #76
Do not force lineends.
Fix c++11 compiling.
Strange shit is happening... how the hell did this happen?.
Add missing util/string.h
Fix MacOS build.
Made PolygonRef and Polygon iterateable
Split fffProcessor and multivolumes into h/cpp files.