franky removes useless code and fixes the build script gen for windows

https://github.com/KhronosGroup/OpenCOLLADA/issues/192
https://github.com/KhronosGroup/OpenCOLLADA/issues/193

a few lines of code have been removed form the CMakeLists.txt since they were just variable set that would get overiden later on

for the libxml and pcre lib, i made them use the opencollada_add_lib macro which is used for everything else. this allows them to be exported properly