This patch fixes the libdir on 64 bit architectures, and creates a new subdirectory in the libdir for Stage's plugin libraries. The directories PROJECT_LIB_DIR (lib or lib64) and PROJECT_PLUGIN_DIR (lib/stage or lib64/stage) are now defined in FindOS.cmake, PROJECT_LIB_DIR is used to install libstage and stageplugin, while PROJECT_PLUGIN_DIR is used to install all of the examples. If you'd prefer to use a different foldername for the plugin directory (like PROJECT-APIVERSION), you only need to change the FindOS.cmake file. I also changed the pkg-config file to reflect the variable library install directory. The patch was created against release 3.2.2, and I tested the library loading to work correctly.