* Fix more utf8 bugs. get_multi, incr, and decr did not support it,
    probably because they weren't tested. Added tests, then fixed support.

* Changed handling of "use bytes" to scope more closely to only those
    areas where needed, using "bytes::length" when needed.
* Added "digest_keys_threshold" feature, so keys only get digested
    if length of key is bigger than the threshold. Default is to digest
    all keys if "digest_keys_enabled" is on. This may be set to "250"
    to only digest keys that would be rejected by memcached.
Adding test for Tie::Scalar and Readonly keys and values. NOTE: many of these are failing.
Gramar fixes to some docs.
* Added t/06_utf8_vals.t to test setting values with utf8 data.
    Currently, these all fail, so they're under a TODO block.

* Added t/20_magic.t to test working with Tie'd and Readonly variables.
    Tie'd and Readonly stuff works, as long as the value doesn't contain utf8 data.
    More TODO's.