Windows: Add GSL dlls to the Win Installer

The libraries `gsl.dll` and `gslcblas.dll` will be installed via the Windows
installer.

Closes issue #333

cmake/BornAgain/InstallDll.cmake

@@ -45,6 +45,18 @@ foreach(lib ${Boost_Additional_Libraries})
     message("    ${UTF_PATH}/${UTF_BASE_NAME}.dll - will be installed in ${destination_lib}")
 endforeach()
 
+## GSL library
+message(STATUS "Installation of GSL library:")
+foreach(lib ${GSL_LIBRARIES})
+    get_filename_component(UTF_BASE_NAME ${lib} NAME_WE)
+    get_filename_component(UTF_PATH ${lib} PATH)
+    list(APPEND BA_Dependencies_WIN32 "${UTF_PATH}/${UTF_BASE_NAME}.dll")
+    install(FILES ${UTF_PATH}/${UTF_BASE_NAME}.dll
+        DESTINATION ${destination_lib} COMPONENT Libraries
+        CONFIGURATIONS [Release|MinSizeRel|RelWithDebInfo])
+    message("    ${UTF_PATH}/${UTF_BASE_NAME}.dll - will be installed in ${destination_lib}")
+endforeach()
+
 ## CERF library
 message(STATUS "Installation of Cerf library:")
 install(FILES ${Cerf_LIBRARIES} DESTINATION ${destination_lib} COMPONENT Libraries)