Solution: Move the macros to a private header.

-Set signaler_port to 0 which allows the OS to find a free port, rather than crashing if 5905 is in use (https://github.com/zeromq/libzmq/issues/1542)
-Added config.hpp to the source list so it shows up in generated projects
-Remove CMAKE_BUILD_TYPE setting for generators that don't use it

Solution: Convert to spaces and remove trailing whitespace in these files.

Fixes tests that were introduced in a previous pull request. See
https://github.com/zeromq/libzmq/pull/1539#issuecomment-132968987

This patch  adds a new member of type deque to the
xpub class that contains pointers to metadata_t.
This deque is then used (alongside pending_data
and pending_flags) to preserve metadata when
copying messages.

The routing id (identity) frame return when reading from
a router doesn't have the same metadata as the "real"
message that follows.
For example, The ZAP "User-Id" property is missing.

This patch attach the "data message"'s metadata
to the "identity message" when it is read from the router.

While sending very large messages (far beyond what fits in a the tcp
buffer, so it takes multiple sendto system calls for it to finish),
zmq_close will close the connection regardless of ZMQ_LINGER.

In case no engine is attached, a pipe->check_read() is needed to look
for the delimiter in the pipe and ultimately trigger the pipe
termination.

However, if there *is* an engine attached, the check_read() looks ahead
and finds the delimiter and terminates the connection even though the
engine might actually still be in the middle of sending a message.

This happens because while the io_thread is still busy sending the data,
the pipe can get terminated and the io thread ends up being terminated.

I had the assertion below fail occasionally when running the libzmq
tests under heavy CPU load on linux 3.16.0-4-amd64.

Despite the old comments, re-initing the msg_t leaks a refcount to
metadata in some situations.

v1_decoder looks like it isn't tested any more, but it seems like a good
idea to fix it because it has the exact same piece of buggy code
v2_decoder does.

Fixes not receiving unsubscription messages in XPUB socket with
ZMQ_XPUB_VERBOSE and using a XSUB-XPUB proxy in front.

This adds two modifications:

- It adds a new flag, ZMQ_XPUB_VERBOSE_UNSUBSCRIBE, to enable verbose
  unsubscription messages, necessary when using a XSUB/XPUB proxy.

- It adds a boolean switch to zmq::mtrie_t::rm () to control if the
  callback is invoked every time or only in the last removal. Necessary
  when a pipe is terminated and the verbose mode for unsubscriptions is
  enabled.