dependency on RCurl

[yihui]

I see the only reason for the dependency on RCurl is to download from https, and according to the feedback I received, *nix users often have to spend a few more minutes figuring out how to install RCurl because of its system dependency libcurl (and we need to install the header files).

I guess this dependency can be removed because:

1. on Windows, you can setInternet2(TRUE)
2. wget is widely available under Linux, so you can call system('wget ...') to download the zip ball

I do not know Mac, though.

[hadley]

The main thing is actually ftpUpload. I do realise RCurl is a bit more of hassle for Linux users, but the focus of devtools is really on windows and mac developers. I expect that people on Linux should find installing packages and compiling from source a little easier.

[yihui]

I see. Thanks!

[hadley]

I did have it as a suggests originally, and I do wish it wasn't such a hassle to install, but I think it makes a lot of things easier to write. I wish that there was a better C/C++ lib - I don't know if you've actually looked at curl at all, but it is totally crazy. All operations are controlled with global flags and there only like 3 functions that actually do anything.