compression of the .fl file.

[muhamadazmy]

We need to support compression of produced .fl file.

• We need to try different algorithms, see which one gives better performance.
• The compressed fl should have an obvious extension, For example .flz if we using gzip.
• rfs then can use .fl, .flz, etc... and decompress. If possible open the .fl for reading in memory directory without having to decompress on disk.