io.sockets: add word addrinfo-error to signal host lookup failures

If the getaddrinfo call fails, and you want to handle that failure in
a structured way, then you need a designated error type to know what
went wrong.
io.sockets: don't need "0 or" for addrinfo.
io.sockets: use must-fail-with for resolve-host errors.
calendar.threads: simplify.
calendar.threads: implement M\ timestamp sleep-until.
calendar: M\ timestamp clone should clone gmt-offset.
calendar: clone timestamps in >gmt and >local-time.
FUEL: Load fuel-mode when factor-mode loads.
FUEL: Customization variable that controls whether fuel-mode is loaded automatically.
removing readme.html.

(github makes the markdown version more awesome^H^H^H^H^H^H^Hlikely
to be used.)
html.parser.utils: adding a simple html escape/unescape.
html.parser.util: removing incomplete html escaping.
html.entities: adding better HTML 5 escaping.
html.entities: reference the table in the w3 specs.
html.entities: slightly better (looking) docs.
html.entities: add a test to show "&amp".
automatically sets up the Factor coding style for Emacs users
html.entities: simpler re-charref.
io.standard-paths.unix: Fix ifconfig test.
dlopen using RTLD_GLOBAL