A little fix request for the packer lib

[Inf0Byt3]

I've been playing with the packer lib for some while now and while using it, i've seen that the pack routines are not buffered. For example if I use AddPackFile() with a couple of 500mb files, all the previous compressed data is hold in the memory and not commited to disk, so it is kinda useless for compressing big files. Gnozal's ZIP lib is buffered, it doesn't exceed a few megs of ram while packing huge files. Could there be done some improvements to the lib?

Thanks!