* handle the PRNG state with R_state nested class
* add a private property R holding PRNG state to Fortuna
* add R_state properties as defined in Cryptography Engineering:
* a generator instance
* a reseed counter
* 32 pools that the collected entropy is to be distributed over
* add initial definition of the Pool object and its initialization
* attempt to initialize PRNG in Fortuna constructor. wrap the
initialization call in a try-catch block like a cultured person
* erase the string used to print data from random_data() after it's been
used
