Merge pull request #51 from hintjens/master

Problem: animate requires rebuild
Merge pull request #53 from hintjens/master

Added more logging support to engine API
Merge pull request #54 from hintjens/master

Fixed server/timeout and other issues
Merge pull request #55 from hintjens/master

Problem: case-sensitive compare on message names
Actually use codec xml class header and source attribute
Documented limitation for send in one step methods.
Merge pull request #57 from sappo/master

Minor fix and documentation update
Added zuuids to the list of supported types
Merge pull request #58 from sappo/master

Added zuuids to the list of supported types
Problem: need hook for server monitoring

Solution: add engine_set_monitor() that calls monitor function
at specified interval using zloop timer.