Improve traj reconstruction (use traj1, vs. old traj + Δy)

[avikde]

Items to do in the future:

• Most of the error in traj reconstruction (use traj1, vs. old traj + Δy) was due to Fext_pdep -- with false, there was a lot of error, but with true, they both yield exactly the same unactErr. What does this mean aboout the overall strategy?
• Better version of fixTraj() that does not just go and apply the inputs from 1..N, and instead does something better

Originally posted by @avikde in #80 (comment)

Also, see #96 (comment) for two more problems caused by fixTraj

• traj becomes asymmetric
• σomax gets exceeded

[avikde]

One good way to approach this may be to use the find delta y optimization that just tries to min delta y but satisfy constraints. I.e. just remove any other param opt from the constraints and the params themselves from the decision vars.