O_BINARY might be defined.

Some unix environments defines O_BINARY.
Added MONGOOSE_NO_USER configuration define.

Low-end systems, not running a proper OS, may not have the
concept of a user.
Added size macros.

On very resource constraind devices you need to be able to
control the size of all buffers and structures placed on the
stack.
MONGOOSE_NO_CGI needs special handling.

MONGOOSE_NO_CGI is implied by both NS_DISABLE_SOCKETPAIR and
MONGOOSE_NO_FILESYSTEM. Thus, so as not to get complaints about
the same define being defined twice, some extra checks are needed.
If socket is about to be closed do not add to [read|write]_set.

If NSG_CLOSE_IMMEDIATELY is on, then the socket will be closed,
which means that (if the socket was added to either read_set or
write_set) the subsequent select will in turn be performed on a
socket that has been closed.

Standard socket implementations seem to ignore a descriptor
referring to a closed socket but LWIP
(http://savannah.nongnu.org/projects/lwip/) crashes. So better
not to add to the sets.
Merge pull request #437 from jhnwkmn/nsf-close-immediately

If socket is about to be closed do not add to [read|write]_set.
Merge pull request #434 from jhnwkmn/no-user

Added MONGOOSE_NO_USER configuration define.
Merge pull request #435 from jhnwkmn/size-macros

Added size macros.
Merge pull request #436 from jhnwkmn/no-cgi

MONGOOSE_NO_CGI needs special handling.
Merge pull request #432 from jhnwkmn/o_binary

O_BINARY might be defined.