Support recovery of passwords of length 16 and above

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I did some tests. For example, due to its caching architecture, if we want to support 64 char passwords with oclHashcat-plus it will require 16gb host memory. Otherwise it wont start. The speed dropped from ~ 3000Mhash/s to ~ 1800Mhash/s. If we choose to support 32 char only its 8gb host memory and ~2400Mhash/s.