Improve file table in libpacker

[lookeypl]

After refactoring Packer and libpacker code add some new functions.

Perform research on methods of keeping file table:

• Maybe holding MD5 is not an optimal solution - compare to keeping pure string (this saves us hashing time, but probably will take longer to naively compare strings).
• Find another way to keep information about file in file table (consider hashing entire file instead of filename only).
• Analyze other hashing algorithms and see which one will perform better (if any). Implement such algorithm in nfCommon.
• If it turns out, that hashing is faster than keeping pure string - implement binary searching to achieve log(n) complexity.

Remember about adding tests for every new section of code you will write.