Update space_utils.c

** sdb2warp_max now returns the max it can AFFORD to go  based on movement allocation. Absolute max is in the specsheet.
** sdb2impulse .. See above..
** sdb2warp_cost(x, factor) returns how many GW you need in movement for factor
** sdb2imp_cost(x, percent) same thing for impulse.
** sdb2cruise_*() are deprecated. Warp/Impulse cruise are part of the specsheet.