* fix Makefile to build in a (more) sensible way (still not really perfect)
* a parse_hostport in common
* fix warnings in render_file
* commandline argument parsing for render_node
* render_remote takes a struct remote_node, maintains its current_load, and actually close the socket after use now
* web_main uses a remote_pool, accepts nodes on the command line, and picks nodes from there for render_remote
* improve _http_render_execute error handling, sends back an error reply now
* ignore SIGPIPE. This hadn't shown up before (probably read-EOF instead), but it uncovered a bug in evhttp that caused an infinite bufferevent_write loop -> oom_killer -> DoS attack
* yes, this commit is missing four new files, those will be included in the next one