make all dimmable lights fully dimmable to any level 0-14

for backward compat, they'll resond to the usual strings, too:

"off" -> 0
"min" -> 3
"med" -> 7
"hi"  -> 11
"max"/"on" -> 14

all dimmable nodes have been renamed to bear the light value in their
names, and aliased.

the non-dimmable lights still respond as before
("off" or n < 4; "on" or n > 3)