ASTRO-DF Refactor

[Grochocinski]

• Moved a lot of variables to instance variables for the class so they wouldn't need to be passed back and forth repeatedly between functions (iterate() requiring 13 values and returning 10 was driving me crazy)
• Extracted common code into functions for increased clarity, the most notable being the adaptive sampling functionality
• Added clamp_with_epsilon function to optimize box constraints
• Changed divide-by-zero behavior to avoid introducing misleading/incorrect values into datasets. Apparently this also fixed the one remaining linux/windows test discrepancy mentioned in Reimplement testing #145, so we can close Floating Point Calculations are not Standardized between Systems #80 😎
• General optimization