Change slope bounds and number of loops in mud_calculator.py

[yucongalicechen]

Problem

For mud_calculator.py, the estimated slope reaches maximum when intensity is large

Proposed solution

To address this, we can increase the slope bounds to make it more flexible. Additionally, increasing the number of loops from 10 to 20 can achieve better results within a reasonable time frame.

Other related improvements could include: (1) write out the estimated mu, diameter, and slit width to args for user's information, (2) give a better docstring.