sending MultiPart in http client Fix #1005

[WebFreak001]

this is also testing the server implementation which made me find #1875

[s-ludwig]

While reviewing the changes, I came to the conclusion that this needs a deeper API change to work efficiently with the non-class streams of vibe-core. What I would propose is to drop the MultiPart(BodyPart)' class(es) completely and change the signature of writeParttovoid writePart(InputStream)(InputStream content, in ref InetHeaderMap headers = emptyHeaderMap) if (isInputStream!InputStream)`. That would avoid the need for a proxy that does dynamic dispatch and destroys all inlining possibilities.

Of course there can still be the convenience overloads that take other kinds of types for content.

[WebFreak001]

@s-ludwig ping

[WebFreak001]

@s-ludwig pong

[WebFreak001]

@s-ludwig bump... I need this yet again...

[WebFreak001]

ping

[vitalka200]

Any plans on merging this? @s-ludwig

[WebFreak001]

bump @s-ludwig

• improved API
• documented everything!
• moved into vibe.inet (because this is a MIME RFC which also applies to mails)
• no longer using my emplace hack which probably broke everything before just because I was too lazy to understand the new vibe-core code, but now instead using proper code
• no internal proxy reading hacks anymore, instead stores the length along with MultiPart
• fixed unittest to actually run