Update Blackjack Lab

Updated the solutions. Removed randomness tests. Combined Mersenne twister with LCG. Cleared up the Blackjack section to be more comprehensive and understandable for students.
Quick typo fix, this is a single sentence because of the comma after random numbers, so we want a lowercase b, "but" rather than "But." In the following comments, such small typos are far from deeply concerning, but are still easy to fix.