statistics changes

- removed statistics gathering that is not precise from step, to be
gathered when events like death and reproduction occur
- proved printFinalStats to StatisticsAgent and renamed to printStats,
since it is called throughout the simulation and not just at the end
- lastNum prey and predator moved to statistics agent
-preyCaught moved to predator class
- predOutRun moved to prey class
statistics, mutators, learning data member

- commented out data members
- commented out initialize method
- added 4 mutators for use with parameters
- iDie: changed to lastMealLow to be consistent with Prey. Value given
by parameter anyway.
- step: modified so that learning only happens if learning is turned on
for predators
statistics

- added statistics gathering during birth and death
- made actualDeathRate static, as repRate is static
- added mutator for actualDeathRate
- step: shuffled the neighbors that are analyzed for learning
- step: modified the loop for learning and counting if predators have
been outrun
parameters, random number generator

- main: added 2 parameters, booleans for prey and predator learning to
be enabled vs disabled
- main: commented out parameters and renamed default rep rate to remove
word "default"
- made clusters a parameter
- constructor: changed clusters to only be created if # of clusters is
> 0
- moved interval here from Animal
- start: changed to use built-in random number generator instead of
local variable
New agent scheduled to print statistics.

New agent scheduled at given intervals to print statistics.  Based on
code that was originally in Animal class, but now it can be run once
per time step (and only the time steps at the set intervals) instead of
with every predator and every prey.