ZENGINE: Optimize integer type usages

The general thought is int is faster than int16 or byte. So if you can afford the
space, use it over int16 or byte. Also, only use int32 when you specifically need
the 32 bits.
ZENGINE: Convert String pointers to const references
ZENGINE: Convert sscanf formats to follow new int lengths
ZENGINE: Initialize the iterator
ZENGINE: Convert _blockSize to an anonymous enum
ZENGINE: Remove redundant class qualifier