Performance improvement for communication client->daemon

WARNING: This changes communication protocol, therefore you have to
recompile powerline-clent and restart powerline-daemon with

powerline-daemon -r

Merged from
https://github.com/ZyX-I/powerline/commit/203a374b54c202d6025828d57d47ad63f571c92f
Merge branch 'master' of github.com:kovidgoyal/powerline-daemon