quick and dirty fix for hiredis bug creating problem with the new redis-cli connect commmand. Also change prompt when redis-cli is not connected

Now the rdbSave* functions return the number of bytes written (or
required to write) in serializing a Redis object, writing to /dev/null
and using ftell (which doesn't work on FreeBSD) isn't needed anymore.

volatile-lru maxmemory policy segfault fixed, thanks to Anthony Lauzon for reporting the problem with the patch. Original patch modified a bit in order to avoid the double lookup if the policy is allkeys-lru

added noeviction policy to redis maxmemory. ZSCORE removed from the list of commands that can't be called when we are low on memory, this command was added in the past for a stupid error.

build redis-server at the end so have a more pleasing to see Make output and the advice to run the test suite at the end.

first attempt to non blocking implementation of slave replication and SYNC bulk data download. Never compiled so far...

Now it is possible to use quoted strings in the redis.conf file accordingly to the sdssplitargs() function capabilities.

Do not update the LRU info on key lookup when we have a saving child. With this trivial change the additional memory used while saving with a background child in presence of many read operations is zero.

redis-cli in interactive mode now prints the time elapsed of the operation performed took more than half a second.

Revert "Function to compute RSS memory usage in a fast way, suitable to be called inside keys eviction loops"

This reverts commit 7d47ecd5.

Revert "Now maxmemory, VM, and everything else uses the fast RSS memory used estimation instead of raw memory reported by zmalloc(). This means that setting maxmemory to 2GB will really have the effect of using up to 2GB of memory."

This reverts commit a3e60027.

Now maxmemory, VM, and everything else uses the fast RSS memory used estimation instead of raw memory reported by zmalloc(). This means that setting maxmemory to 2GB will really have the effect of using up to 2GB of memory.