add -clean option to runtests.bat/runtests.py
add -clean option to runtests.bat/runtests.py

kjk/the_silver_searcher,leeonix/the_silver_searcher,leeonix/the_silver_searcher,vehar/the_silver_searcher,leeonix/the_silver_searcher,kjk/the_silver_searcher,vehar/the_silver_searcher,kjk/the_silver_searcher,kjk/the_silver_searcher,vehar/the_silver_searcher,vehar/the_silver_searcher,vehar/the_silver_searcher,leeonix/the_silver_searcher,vehar/the_silver_searcher,leeonix/the_silver_searcher,leeonix/the_silver_searcher,kjk/the_silver_searcher,kjk/the_silver_searcher