Moves OrderedDefaultDict from util to collections.
Moves DeflateDecompressor, gzip_decompress from util to decompression.
Moves sleep,TimedOut,wait_future,AdjustableSemaphore from util to async.
Moves string releated functions from util to string module.

Moves to_bytes, to_str, normalized_codec_name, detect_encoding,
try_decoding, format_size, printable_bytes, coerce_str_to_ascii from
util to string.
Merge branch 'topic/code_cleanup' into develop