Change lctl lovconfig command into lov_getconfig, and add lov_setconfig.

Change lctl lovconfig command into lov_getconfig, and add lov_setconfig.
Update all scripts/docs which refer to the lovconfig command.

lov_getconfig compiles OK, and does not affect normal operation, but it
is not working yet (user-space segfault) and I need to run it on a real
system (can't run GDB under UML).