Add clipboard(x), clipboard() for windows

[quinnj]

I'm not an expert on the Windows API by any means, but this is the function that I've had in my .juliarc for quite a while and have used fairly frequently. Please let me know of appropriate changes that need to be made.

[quinnj]

Probably best if @vtjnash and/or @loladiro review this.

[StefanKarpinski]

Since no one can be depending on this yet, it's safe enough to merge and then adjust as necessary.

[vtjnash]

Seems fine. Note that it needs to be fixed to use bytestring/sizeof instead of string/length. Also, does windows accept UTF8 as Unicode? I thought it did everything with either ASCII or UTF16.

[StefanKarpinski]

Unicode not an encoding, so technically calling this CF_UNICODETEXT as they seem to is meaningless. Classic Microsoft brain damage. Without further documentation, it's hard to say whether this means UTF-8 or UTF-16, but you could probably find out pretty easily by experimenting with sending data to Notepad and back.

[quinnj]

I noted in another PR that the CF_UNICODETEXT is UTF-16. Recommendations I've seen say to use CF_TEXT unless you're explicitly using UTF-16 strings.

[StefanKarpinski]

Ok, fixed it. Shame that we won't support Unicode copy-and-paste on Windows though.

[vtjnash]

our unicode support is pretty bad on windows anyways: #1919

[StefanKarpinski]

Arguably, Windows' support for sane string processing is what's lacking, but point taken.