Updated README.
Merged pull request #554
Rename "buffer" to "mongo_buffer".

The original declaration put "buffer" in the global scope, but we also used
"buffer" as a variable name. We can't really do that (says GCC/ANSI C).

Conflicts:
	cursor_shared.c
Removed the new file, as that should not be part of this PR.
Merged pull request #561
Remove unused stuff
Remove unused flag (MONGO_CURSOR) and multi-declaration of mongo_cursor_free_le
We don't do threading: Killing unused code
Got no idea where this came from, but its not used
Kill the Cursor right away, rather then going down complex checks
Remove cursor tracking leftovers since 1.2

Cursors used to be thread-safe and almost-persistent
None of this logic is needed anymore
Remove unused struct

Cursors now register a callback on the connection, so when it is closed
(for any reason) we kill the cursors associated with that connection.
The cursors are also automatically killed during object dtor
Remove dead code
More unused weirdness
Lift MAKE_COPY_ZVAL from php-src rather then use our homebrewed version

It is defined in 5.3, just need it for 5.2 support
More unused stuff