New simple neighborhood constant function, transition time function updated

Completely different from old function called shc_lv_neighborhood(), which has been removed. This is just a simple function that converts Beta into the the neighborhood-size.

shc_lv_meanperiod() and shc_lv_transitiontime() updated to used shc_lv_neighborhood(). Other fixes and improvements to shc_lv_transitiontime() too.

Signed-off-by: Andrew D. Horchler <adh9@case.edu>
Minor fixes to initial condition function

shc_lv_ic() cleaned up a bit and now uses shc_lv_neighborhood().

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