Performance and latency improvements

Charles Briquel submitted some performance related pull requests which should be integrated into the next version.

https://github.com/quickfix-j/quickfixj/pull/32
https://github.com/quickfix-j/quickfixj/pull/34
https://github.com/quickfix-j/quickfixj/pull/35
https://github.com/quickfix-j/quickfixj/pull/36
https://github.com/quickfix-j/quickfixj/pull/37
https://github.com/quickfix-j/quickfixj/pull/39
https://github.com/quickfix-j/quickfixj/pull/40
https://github.com/quickfix-j/quickfixj/pull/41
https://github.com/quickfix-j/quickfixj/pull/42