sim_steps: Simulate conditional steps.
In a-parton/CTStepTurn: Fitting the continuous-time step-and-turn movement model

sim_steps simulates a set of conditional steps.

1 2	sim_steps(step_mean, step_covar, A, loc_covar_error, error_mean, error_covar, loc_step_covar, start_loc, fixed_locs, type)

`step_mean`	Vector, mean of unconditional steps.
`step_covar`	Square matrix, covariance of unconditional steps.
`A`	linear constraint matrix.
`loc_covar_error`	Square matrix, covariance of observed locations (including error if applicable).
`error_mean`	Vector, mean of the errors.
`error_covar`	Square matrix, covariance of the errors.
`loc_step_covar`	Matrix, covariance between unconditional steps and the observed locations.
`start_loc`	Vector, length 2, giving the location at the start of the section.
`fixed_locs`	Vector, giving the observed locations along the section.
`type`	Character ("start", "middle", "end") describing where on the full path the section is from.