Copy movement information for old enemies from original flare

The changes in this commit are taken from the files
git://github.com/clintbellanger/flare-game.git after the floating point
stuff was merged.

This commit only affects the old enemies.

Signed-off-by: Stefan Beller <stefanbeller@googlemail.com>
Change all ng_* enemies as well as alpha_demo enemies
powers: replace range, radius, speed, speed_variance by tile based distance
Merge pull request #39 from stefanbeller/fp_movement

Floating point movement