Counts all the set bits in the BitArray
auto a = BitArray([0, 1, 1, 0, 0, 1, 1]); assert(a.count == 4); BitArray b; assert(b.count == 0); bool[200] boolArray; boolArray[45 .. 130] = true; auto c = BitArray(boolArray); assert(c.count == 85);
See Implementation
Counts all the set bits in the BitArray