Return a stack of observations if several parameters are given

[kateharborne]

In telescope() or observing_strategy(), if a sequence of observations are defined we would like the code to automatically iterate through these observations and return the outputs as a stack of observations.

This could mean producing the observations at a prescribed range of inclinations/twist angles, or a range of seeing conditions, etc.

Returned outputs should be appropriately assigned names if being written to environment variables, or individual FITS files if being written to file.