Forgotten a semicolon
Added the speed test utility

It measures the speed of each generator
by generating 10 million random numbers.

Note that when generating 32 bit numbers
with the 64 bit generators, we have to
create just 5 million, because a 64 bit
number can be split in two 32 bits.

Also, the 64 bit numbers are created from
32 bit generators by concatenating two
numbers.
Added a gitignore
Added a rule for making the speed test in the Makefile
Seems that iterating just in integers is faster.
Added a little information to parisi generator
Added the Isaac generator
Definite merge of the isaac generator