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.
Sometimes, labs move and are changed around, so we never reference a lab based on placement. Instead, we look up the label of the last lab and reference it accordingly using
In Lab \ref{<label name>}, weak PRNGs, etc.