[sr-dev] new version of lcr module

i just pushed a new version of lcr module, which resulted from discussions on the mailing lists.

most important new feature is support for any number of independent lcr instances, which improves virtualization of sr. for example, different domains can now manage their own least cost routing to their own gws.

i also replaced aliveness check with new defunct_gw() function, which script writer can use to defunct an unresponsive or busy gw for a desired period of time.

in order to keep lcr module manageable, i removed gw group related functions (which were not efficient anyway). if someone is using them, i hope that they can be replaced by lcr instances.

-- juha