server doesn't require any auth at all and then we just continue nicely. We
now have an extra bit in the connection struct named 'authprobe' that is TRUE
when doing pure "HTTP authentication probing".

anything newer than that

file until it is actually being uploaded.
Make sure we build and still work with HTTP disabled - the SSL code might use
the boundary string for some random seeding.

might be used uninitialized

a host name that resolves to multiple IP addresses.

path after a transfer.

--disable-http, which thus builds a libcurl without HTTP support.

keep the API complete at all times

An Alexander Krasnostavsky fix.

to/from, based on a suggestion from Alexander Krasnostavsky

doing proxy authentication.

previous difference was not clear nor documented properly). They can now both
be used interchangeably, but we prefer UPLOAD to PUT since it is a more
generic term.