Definitely replace class name Light with sreLight

Signed-off-by: Harm Hanemaaijer <fgenfb@yahoo.com>
Rename all class names so that they are prefixed with "sre"

Rename all class type names so that they are prefixed with
"sre" (eg. sreLight). This provides a more consistent API
and may help name-space collisions.

Signed-off-by: Harm Hanemaaijer <fgenfb@yahoo.com>