Changed to use zlibEx (1.2.8). Use constants. Less memory use

Majority of zip library tries to do everything in memory in one
continuous chunk. Added support to make some things stream based, and
not blow the 2GB virtual memory limit.
Fixed memory leak

FillChar or ZeroMemory on a record that contains strings is bad; it
leaves AnsiStrings/WideStrings/Variants/Arrays stranded and it leaks
memory. Ripped out FillChar to initialize a structure and replaced it
with assignment of the null record.