use normal distribution on initial random individual creation

initial default range tweaked way down
rename "POP" template parameter to "POPSIZE"
added RunOneGeneration() method - generations can now be run one at a time
added SetRange(i,min,max) method
added a decent amount of comments through main algorithm and class declaration

derand.h

@@ -25,6 +25,8 @@ namespace DE
 	
 		double RandDouble();
 		double RandDouble(double min, double max);
+
+		double RandGaussian(double mean, double variance);
 	
 		u32 RandU32();
 		u32 RandU32(u32 min, u32 max);