Add zlib

I didn't know how to integrate zlib with cmake. It seems just including the existing CMakeLists.txt doesn't work. As it contains some potentially important parts about assembler code, I tried to copy it and only change the parts necessary to build successfully. However, I am not sure this is correct.

Another problem is the naming of the compression option. As far as I understand, the algorithm is called deflate. Additionally, there exist two formats called zlib an gzip in addition to the raw deflate output. HDF5 calls the compression filter deflate, but seems to use the zlib format. To make this even more confusing, h5py calls this filter gzip. I decided to call the filter deflate as in HDF5, although zlib might be more accurate.