Initial support for key expire times with millisecond resolution. RDB version is now 3, new opcoded added for high resolution times. Redis is still able to correctly load RDB version 2. Tests passing but still a work in progress. API to specify milliseconds expires still missing, but the precision of normal expires is now already improved and working.

entry. Field name of hash entry union modified for clarity.

dict.c: added macros in dict.h to set signed and unsigned 64 bit values directly inside the hash entry without using additional memory.

dict.c: added two lower level methods for directly manipulating hash entries. This is useful in order to set 64 bit integers as values directly inside the hash entry (in order to save memory), without casting, and even in 32 bit builds.

Multi bulk optimization for creating big objects without copying data is no longer optional, #ifdefs removed. Also debugging messages removed.

to 16k, request buffer size is no longer destroyed when emtpy and large
(better fix needed). Redis clients static output buffer set to 16k as
well.

further optimizations for the multi bulk protocol parsing code when big objects are transmitted to Redis.

sdsIncrLen() / sdsMakeRoomFor() used to avoid copying to intermediate buffer while reading the client query.

sdsMakeRoomFor() exposed as public API. sdsIncrLen() added. Both the changes make it possible to copy stuff from a system call to an sds buffer without the need of an additional buffer and copying overhead.

maxclients configuration is now implemented dealing with the actual process rlimits. Setting maxclients to 0 no longer makes sense and is now invalid, the new default is 10000.
See issue #162 for more information.

It is now possible to disable password authentication via CONFIG SET. Thanks to Jan Oberst. This closes issue #171.

If a Lua script executes for more time than the max time specified in the configuration Redis will log a warning, and will start accepting queries (re-entering the event loop), returning -SLOWSCRIPT error for all the commands but SHUTDOWN that remains callable.

Clear the AOF rewrite scheduled flag once an AOF rewrite is triggered. Fix for issue #161, probably fixing 159 as well.