make logger.debug conditional,
make logger.debug conditional,

even though the actual debug message doesn't get written, the string
still gets evaluated, which 1) is not time efficient and 2) can
introduce errors in some cases, because a Feature may be converted to a
string when evaluating the message before it's ready.

daler/gffutils,daler/gffutils,hjanime/gffutils,hjanime/gffutils