Merge pull request #133 from mknoszlig/master

Problem: Socket functions should only be responsible for send.
Problem: generates duplicate typedefs with zproject

Solution: guard typedef generation against zproject typedefs.
Merge pull request #135 from mknoszlig/master

Problem: server can't receive decoded message via generated codec.
Merge pull request #134 from hintjens/master

Problem: generates duplicate typedefs with zproject
Problem: can't specify where to send Java and Clojure output

Solution: add -root_path:xxx option, so from src, you can set this
to -root_path:../main.

It's still unclear where the best place is for model files in a
multilanguage project. To be tweaked. For now they're in src.
Merge pull request #136 from hintjens/master

Problem: can't specify where to send Java and Clojure output