helpers: fix move_contents_to() not moving air

fixes #5232

Signed-off-by: Mloc-Argent <colmohici@gmail.com>
lighting: fix + optimize colored lights

turfs now directly hold color lumcounts
overlay is averaged + rounded from that instead of strings
overall colored lumcount is now rounded properly
fixes having thousands of lighting subareas after a fire
fixes #5417

Signed-off-by: Mloc-Argent <colmohici@gmail.com>
Merge pull request #5425 from Mloc/bs12-lightopt

shuttle + lighting fixes