Add HMSETIF (renamed from HMSETCK)

This is HMSETCK from @tsee with a few changes to integrate
better into more common Redis usage.
Improve HMSETNX implementation

We don't need copy/paste implementation of hash adding, we can call
hmsetCommand() directly for us.

Note: this changed the return value of HMSETNX from 1 on success to
OK on success (the return value is now provided by hmsetCommand()
instead of by HMSETNX directly).  On error, HMSETNX still returns 0.
Add t_zset.c prototypes directly to zset.c

We were relying on dynamic.h for these, but that doesn't
work when we're copying files into redis/src
Fix zsetScore() function definition

Since true/false are defined as 1/0, you can return true/false
from a function with return type "double."

You can, but it's wrong.  Very wrong.
Select proper DB for GEOADD with varargs
Add geo tests for the Redis test system
Add script copying geo into Redis source tree

The script copies all files and even manipualtes some Makefiles
for you, but you need to add and updates some Makefiles on your
own as well.