Return "WRONGTYPE" error on PF* type mismatch.
Initial HyperLogLog tests.
Changed HyperLogLog hash seed to a non-zero value.

Using a seed of zero has the side effect of having the empty string
hashing to what is a very special case in the context of HyperLogLog: a
very long run of zeroes.

This did not influenced the correctness of the result with 16k registers
because of the harmonic mean, but still it is inconvenient that a so
obvious value maps to a so special hash.

The seed 0xadc83b19 is used instead, which is the first 64 bits of the
SHA1 of the empty string.

Reference: issue #1657.
tryObjectEncoding() refactoring.

We also avoid to re-create an object that is already in EMBSTR encoding.
PFCOUNT: always unshare/decode the object.

This will be a non-op most of the times since the object will be
unshared / decoded, however it is more technically correct to start this
way since the object may be decoded even in the read-only code path.
ZRANGEBYLEX and ZREVRANGEBYLEX implementation.
Add casting to match printf format.

adjustOpenFilesLimit() and clusterUpdateSlotsWithConfig() that were
assuming uint64_t is the same as unsigned long long, which is true
probably for all the systems out there that we target, but still GCC
emitted a warning since technically they are two different types.