Fix pontential integer overflows

[jeremykubica]

This PR includes a series of changes meant to support large image sizes:

• Change the starting coordinate in Trajectory from short to int.
• Change all instance of the computation and storage of the number of pixels per image to a unsigned 64.
• Allow for greater than an int’s worth of result trajectories to be sorted in a TrajectoryList during stamp creation.

Also a few clean ups:

• Fix some docstring formats
• Change loops over the dimensions from int to unsigned int for clarity.
• Change the time lookup in extract_psi_or_phi_curve() from float to double to be consistent with the precision used in the rest of the code.