Add support for fragment in parse_url and build_url

[craigcitro]

Any opposition to adding support for the fragment? It looks like parse_url already grabs it.

[hadley]

Probably just an oversight

[craigcitro]

(Amended my commit when I noticed something trivial; on the off chance that bit me just lemme know and I'll fix.)

[hadley]

Commit looks fine but I'll show you a nicer idiom when I'm at my computer

[craigcitro]

+1 -- this means my not-so-secret plan to learn R by having you review my code is working. ;)

[hadley]

I'd write it like:

str_c(scheme, "://", login, hostname, port, "/", path, params, query, 
    if (!is.null(url$fragment)) "#", fragment)

str_c() automatically drops zero-length inputs, which is a really useful convention because it an if without an else block returns NULL for FALSE.

[craigcitro]

ah, nice -- done.

if you want, i can do the same to the username/password lines above, since that would all compact down nicely. (and probably add a stop for the case of password without username?)

[hadley]

Yes please!

[craigcitro]

done -- PTAL

[hadley]

Looks good. Can you please add a bullet to the NEWS?

[craigcitro]

ok, added a note and squashed.