Fixing inject: it was failing when there was 1 or >2 sources

string to number API is now more strict not accepting spaces before or after the number. A few tests converted to match the new error messages using the word float instead of double.

Fixed issues with expire introduced with latest millisecond resolution feature. Many time_t were not converted to long long, and one time() call was not replaced with mstime().

new tests for EXPIRE family functions, new millisecond precision, and new millisecond argument variants.

high resolution expires API modified to use separated commands. AOF transation to PEXPIREAT of all the expire-style commands fixed.

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.

speed-regression.tcl: move tests, data size, requests in global vars that will be changed via command line options.

speed-regression.tcl script: killing previously tested instance fixed. Don't run if there is already an instance running in the same port.