refactor websocket server to allow invoking as module
launch websocket server along with proxy server
use relative path names in traces
initial support for source locations with proxy server

Still a bit hackish.  We're still storing a single IID map
file, and you need to kill the proxy server to write the footer.
ensure messages to websocket server respect MAX_BUF_SIZE
remove Jalangi modifications from index.html files
add index_jalangi_.html for go
more index_jalangi_.html files