started the entropy functions
Merge branch 'master' of github.com:Siacoin/Sia
Added some entropy functions, with some tests
added skeletons for the crypto fuctions
Update Makefile, address github PR comments

'make' now no longer runs 'make test', 'make test' is no longer
automatically verbose, and 'make test-verbose' is verbose. Renamed
'Entropy()' to 'EntropyBytes' (still debating that name though), renamed
'MergeEntropy()' to 'DRNGSeed' and made some general performance
enhancements, and improved the syntax and readability of the code.
Merge pull request #9 from DavidVorick/master

Add entropy functions