Class EpochDifficultyConverter

Convert matching bits to actual difficulty value Difficulty = 2^bits

This ensures that:

• 20 bits = difficulty of 1,048,576
• 30 bits = difficulty of 1,073,741,824
• 40 bits = difficulty of 1,099,511,627,776

So a 40-bit share is worth 1,048,576x more than a 20-bit share, not just 2x more

Format difficulty for display