Install to full directory

The pkg-config template uses the _FULL_ variables while the install happens without the prefix.
This addresses #116

CMakeLists.txt

@@ -137,10 +137,10 @@ PKG_CONFIG_USE_DEPENDENCY(${PROJECT_NAME} eigen3)
 INSTALL(TARGETS ${PROJECT_NAME}
   EXPORT ${TARGETS_EXPORT_NAME}
   PUBLIC_HEADER
-  INCLUDES DESTINATION ${CMAKE_INSTALL_PREFIX}/include
-  LIBRARY DESTINATION ${CMAKE_INSTALL_PREFIX}/lib
-  ARCHIVE DESTINATION ${CMAKE_INSTALL_PREFIX}/lib
-  RUNTIME DESTINATION ${CMAKE_INSTALL_PREFIX}/bin)
+  INCLUDES DESTINATION ${CMAKE_INSTALL_FULL_INCLUDEDIR}
+  LIBRARY DESTINATION ${CMAKE_INSTALL_FULL_LIBDIR}
+  ARCHIVE DESTINATION ${CMAKE_INSTALL_FULL_LIBDIR}
+  RUNTIME DESTINATION ${CMAKE_INSTALL_FULL_BINDIR})
 
 ADD_HEADER_GROUP(${PROJECT_NAME}_HEADERS)
 ADD_SOURCE_GROUP(${PROJECT_NAME}_SOURCES)