module-loader: change naming

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
module: add callback for enable and disable

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
module: implement enable/disable hooks

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
module: set widget sensitivity for enable/disable

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>