Much faster inter-passage transition time calculation and parameter finding

Adjusted integration method in shc_lv_transitiontime() to speed it up by an order of magnitude or so. Much faster. A simple approximation based on the transition time for a marginally stable system is is used to estimate step-size. Runge-Kutta now used for time-step counting with a simple step-size reduction scheme to converge on the transition time, Tt.

The new shc_lv_transitiontime() makes shc_lv_params much faster again. Additionally, a correction on the initial guess for Alpha was added based on shc_lv_transitiontime().

Signed-off-by: Andrew D. Horchler <adh9@case.edu>
Initial condition-finding function sped up and cleaned up.

shc_lv_ic() overhauled. Still needs work and is still a hack, but it's faster. The definition of A0 was flipped (again) - pass in Beta-Delta for an initial condition starting at Beta-Delta. Better heuristics are used to guess integration step sizes.

Signed-off-by: Andrew D. Horchler <adh9@case.edu>