bugfix around get_drop_probability()
nb_values missing in types.db; renaming as cache_size
renamed the option to CollectInternalStats; renamed 'internal' to 'collectd'; no more lock when not recording internal stats
Merge branch 'patch/internal_statistics' into release/5.4.0
Merge branch 'patch/limit_write_queue_length_bugfix' into release/5.4.0