Message codec improvements

This JIRA covers improvements made to the codec, especially lists and maps.

The work is based on https://github.com/rhs/qpid-proton-old/tree/codec/proton-j/src/main/java/org/apache/qpid/proton/codec2

The above referenced code, is quite an improvement with respect to writing lists, maps and strings over the existing codec.

Simply put the writeList and writeMap methods in the old encorder is about ~10 times slower than the new encorder.
If I run with a sufficiently large set of strings, the old encorder is about ~2 times slower than the new encorder.