soup-misc-private.h: Fix the single-include #define

Pointed out by various people on multiple occasions until eventually I
remembered to fix it...
tests: parallelize proxy-test to make it faster

TODO: parallelize auth-test and timeout-test, make it easier to use.
valgrindage
Added Marathi Translations
Added German translation
SoupSessionAsync: fix the idle_run_queue source handling (again)

The previous code checked priv->disposed after the session was freed
sometimes...
SoupSession: make queue items hold a ref on the session

Historically, messages sent via soup_session_queue_message() did not
hold a ref on the session, and unreffing the session when messages
were in progress would cancel them. This is ugly internally though,
and at any rate, depends on being able to know for sure that no one
else is secretly holding a ref on the session.

So, fix it so that pending messages hold a ref on the session, and you
need to use soup_session_abort() before unreffing if you want to
cancel everything.

If it turns out that this breaks things it can be reverted before
2.40...
Added Bengali India Translations
Added Entry for Bengali India and fixed a wrong sequence in the list
Updated Traditional Chinese translation(Hong Kong and Taiwan)
Added uk translation
SoupMessage: Add SOUP_MESSAGE_IDEMPOTENT flag

In particular, this lets the app indicate that it's OK to use an
existing connection when sending a POST.

https://bugzilla.gnome.org/show_bug.cgi?id=681493
SoupContentSniffer: removed several unused function arguments

Removed the SoupMessage argument from various sniffing functions as it isn't
really used for sniffing.

https://bugzilla.gnome.org/show_bug.cgi?id=682112
SoupContentSnifferStream: added can_poll() implementation

Done in terms of the base_stream can_poll() interface. It was not needed to
read resources from network as the underlying streams were all pollable.
This will be used later to sniff locally cached resources. The file streams are
not pollable so we must implement the can_poll() in order to use "normal"
read() calls instead of the read_nonblocking().

https://bugzilla.gnome.org/show_bug.cgi?id=682112
SoupCache: simplify the usage of soup_cache_entry_remove()/free()

Added a new parameter to soup_cache_entry_remove() that instructs the function
to delete the cached resource file if TRUE. It also unconditionally frees
the resources allocated by the entry by calling soup_cache_entry_free().

https://bugzilla.gnome.org/show_bug.cgi?id=681509
SoupCache: moved data from SoupCacheEntry to the writing fixture

The entry fields "current_writing_buffer", "got_body", "stream", and "error"
where only used during the writing phase. Therefore we do not need to keep
all of them in memory in the SoupCacheEntry structure.

https://bugzilla.gnome.org/show_bug.cgi?id=681509
SoupCache: delete untracked files in soup_cache_clear()

Delete all the files in the cache directory when clearing the cache even if
they aren't coupled with any cache entry.

https://bugzilla.gnome.org/show_bug.cgi?id=681509
Make it possibe to request the boundary be discarded by SoupFilterInputStream

This makes it easier to implement streams that discard the boundary, like
SoupMultipartInputStream.

https://bugzilla.gnome.org/show_bug.cgi?id=656684
Add SoupMultipartInputStream for handling multipart responses

SoupMultipartInputStream can be used by the API user to wrap the input
stream, and provides API to obtain the next part and its headers,
using a SoupFilterInputStream internally for buffer management.

https://bugzilla.gnome.org/show_bug.cgi?id=656684
Add missing file for last commit