More container and tree changes on all platforms regarding memory. This should fix GTK3 memory leaks I wasn't previously aware of... but it will cause all platforms to leak memory if strings returned from dw_container_query_start(), dw_container_query_next() and dw_tree_get_title() are not freed with dw_free() when using version 3.

# Set these here to change the version for all platforms
DW_MAJOR_VERSION=2
DW_MINOR_VERSION=5